The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A248795

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A248795

Numbers n such that Product_{d|n} phi(d) = Product_{d|(n+1)} phi(d) where phi(x) = Euler totient function (A000010).
(history; published version)

#19 by Michel Marcus at Sun Nov 23 16:17:42 EST 2014

DATA

1, 3, 5, 15, 255, 65535, 2200694, 2619705, 6372794, 40588485, 76466985, 81591194, 118018094, 206569605, 470542485, 525644385, 726638834, 791937614, 971122514, 991172805

EXTENSIONS

a(10)-a(1720) from Michel Marcus, Nov 23 2014

STATUS

proposed

editing

Discussion

Sun Nov 23

16:18

Michel Marcus: done

#18 by Jaroslav Krizek at Sun Nov 23 15:44:34 EST 2014

STATUS

editing

proposed

#17 by Michel Marcus at Sun Nov 23 14:30:24 EST 2014

DATA

1, 3, 5, 15, 255, 65535, 2200694, 2619705, 6372794, 40588485, 76466985, 81591194, 118018094, 206569605, 470542485, 525644385, 726638834

EXTENSIONS

a(10)-a(1517) from Michel Marcus, Nov 23 2014

#16 by Michel Marcus at Sun Nov 23 12:22:08 EST 2014

DATA

1, 3, 5, 15, 255, 65535, 2200694, 2619705, 6372794, 40588485, 76466985, 81591194, 118018094, 206569605, 470542485

EXTENSIONS

a(10)-a(1415) from Michel Marcus, Nov 23 2014

Discussion

Sun Nov 23

12:22

Michel Marcus: one more term

#15 by Michel Marcus at Sun Nov 23 11:39:37 EST 2014

DATA

1, 3, 5, 15, 255, 65535, 2200694, 2619705, 6372794, 40588485, 76466985, 81591194, 118018094, 206569605

EXTENSIONS

a(10)-a(1214) from Michel Marcus, Nov 23 2014

STATUS

proposed

editing

Discussion

Sun Nov 23

11:39

Michel Marcus: program stll running

#14 by Michel Marcus at Sun Nov 23 09:33:07 EST 2014

STATUS

editing

proposed

Discussion

Sun Nov 23

10:21

Michel Marcus: added more terms and a prog
more terms to come

#13 by Michel Marcus at Sun Nov 23 09:32:49 EST 2014

DATA

1, 3, 5, 15, 255, 65535, 2200694, 2619705, 6372794, 40588485, 76466985, 81591194

EXTENSIONS

a(10)-a(12) from Michel Marcus, Nov 23 2014

#12 by Michel Marcus at Sun Nov 23 08:49:21 EST 2014

PROG

(PARI) lista(nn) = {d = divisors(1); vcur = prod(k=1, #d, eulerphi(d[k])); for (n=2, nn, d = divisors(n); vnext = prod(k=1, #d, eulerphi(d[k])); if (vnext == vcur, print1(n-1, ", ")); vcur = vnext; ); } \\ Michel Marcus, Nov 23 2014

STATUS

proposed

editing

#11 by Jaroslav Krizek at Fri Nov 21 11:41:40 EST 2014

STATUS

editing

proposed

Discussion

Fri Nov 21

11:47

Michel Marcus: Did you check my terms ?

12:13

Jaroslav Krizek: Ok.

12:39

Michel Marcus: good
I let extend the related A248796 sequence, ok ?

13:10

Michel Marcus: I meant: I let you extend ... , ok ?

#10 by Jaroslav Krizek at Fri Nov 21 11:41:26 EST 2014

COMMENTS

Corresponding values of P_a(n) = Product_{d|a(n)} phi(d): 1, 2, 4, 64, 268435456, 1329227995784915872903807060280344576, … Conjecture: values P_a(n) are any powers of 2. For n = 1..6; a(n) = 2^k where k = 0, 1, 2, 6, 28, 120. Conjecture: sequence of integers k is union of {0, 2} and multiply-perfect numbers A007691.

STATUS

proposed

editing