The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A064498

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A064498

Numbers k such that the sum of unitary divisors of k^2 is a square.
(history; published version)

#30 by Alois P. Heinz at Sat Apr 13 15:24:55 EDT 2024

STATUS

reviewed

approved

#29 by Stefano Spezia at Sat Apr 13 15:15:12 EDT 2024

STATUS

proposed

reviewed

#28 by Jon E. Schoenfield at Sat Apr 13 15:13:01 EDT 2024

STATUS

editing

proposed

#27 by Jon E. Schoenfield at Sat Apr 13 15:12:54 EDT 2024

KEYWORD

easy,nonn

nonn

STATUS

approved

editing

#26 by N. J. A. Sloane at Fri May 06 13:13:51 EDT 2022

CROSSREFS

Cf. A034448 (usigma), A008847 (similar , with sigma).

Discussion

Fri May 06

13:13

OEIS Server: https://oeis.org/edit/global/2941

#25 by OEIS Server at Sun Aug 04 05:50:18 EDT 2019

LINKS

Amiram Eldar, <a href="/A064498/b064498_1.txt">Table of n, a(n) for n = 1..1000</a> (terms 1..100 from Harry J. Smith)

#24 by Michel Marcus at Sun Aug 04 05:50:18 EDT 2019

STATUS

reviewed

approved

Discussion

Sun Aug 04

05:50

OEIS Server: Installed new b-file as b064498.txt.  Old b-file is now b064498_1.txt.

#23 by Joerg Arndt at Sun Aug 04 05:14:18 EDT 2019

STATUS

proposed

reviewed

#22 by Michel Marcus at Sun Aug 04 04:50:10 EDT 2019

STATUS

editing

proposed

#21 by Michel Marcus at Sun Aug 04 04:50:01 EDT 2019

PROG

(PARI) {usigma(n, s=1, fac, i)= fac=factor(n); for(i=1, matsize(fac)[1], s=s*(1+fac[i, 1]^fac[i, 2]); ); return(s); } for(n=1, 10^6, if(issquare(usigma(n^2)), print1(n, " ")))

for(n=1, 10^6, if(issquare(usigma(n^2)), print1(n, " ")))

(PARI) usigma(n)= { local(f, s=1); f=factor(n); for(i=1, matsize(f)[1], s*=1 + f[i, 1]^f[i, 2]); return(s) } { n=0; for (m=1, 10^9, if (issquare(usigma(m^2)), write("b064498.txt", n++, " ", m); if (n==100, break)) ) } \\ _Harry J. Smith_, Sep 16 2009

{ n=0; for (m=1, 10^9, if (issquare(usigma(m^2)), write("b064498.txt", n++, " ", m); if (n==100, break)) ) } \\ Harry J. Smith, Sep 16 2009

STATUS

proposed

editing