The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A231170

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A231170

Semiprimes with equal number of even and odd digits.
(history; published version)

#16 by Harvey P. Dale at Mon May 05 16:18:45 EDT 2014

STATUS

editing

approved

#15 by Harvey P. Dale at Mon May 05 16:18:31 EDT 2014

MATHEMATICA

Select[Range[2500], PrimeOmega[#]==2&&Count[IntegerDigits[#], _?OddQ] == IntegerLength[#]/2&] (* Harvey P. Dale, May 05 2014 *)

STATUS

approved

editing

#14 by T. D. Noe at Thu Nov 07 14:09:09 EST 2013

STATUS

editing

approved

#13 by T. D. Noe at Thu Nov 07 14:09:01 EST 2013

LINKS

T. D. Noe, <a href="/A231170/b231170.txt">Table of n, a(n) for n = 1..10000</a>

MATHEMATICA

semiPrimeQ[n_Integer] := If[Abs[n] < 2, False, (2 == Plus @@ Transpose[FactorInteger[Abs[n]]][[2]])]; fQ[n_] := Module[{d = IntegerDigits[n], len}, len = Length[d]; EvenQ[len] && len == 2*Count[d, _?(EvenQ[#] &)]]; Select[Range[2500], semiPrimeQ[#] && fQ[#] &] (* T. D. Noe, Nov 07 2013 *)

STATUS

approved

editing

#12 by Alois P. Heinz at Thu Nov 07 06:47:17 EST 2013

STATUS

editing

approved

#11 by Alois P. Heinz at Thu Nov 07 06:47:06 EST 2013

EXTENSIONS

More terms from Alois P. Heinz, Nov 07 2013

#10 by Alois P. Heinz at Thu Nov 07 05:52:07 EST 2013

DATA

10, 14, 21, 25, 34, 38, 49, 58, 65, 69, 74, 85, 87, 94, 1003, 1007, 1018, 1027, 1041, 1043, 1047, 1067, 1081, 1094, 1126, 1142, 1186, 1203, 1205, 1207, 1214, 1227, 1234, 1238, 1241, 1243, 1247, 1261, 1263, 1267, 1285, 1294, 1306, 1322, 1346, 1366, 1382, 1401

#9 by Alois P. Heinz at Thu Nov 07 05:50:31 EST 2013

STATUS

proposed

editing

#8 by Jonathan Vos Post at Tue Nov 05 08:21:12 EST 2013

STATUS

editing

proposed

Discussion

Tue Nov 05

13:00

Joerg Arndt: Get Pari/gp, it's free;  there is even a free CAS (called Sage)!

Thu Nov 07

05:50

Alois P. Heinz: 1003 =  17 * 59 is missing.

#7 by Jonathan Vos Post at Tue Nov 05 08:21:02 EST 2013

DATA

10, 14, 21, 25, 34, 38, 49, 58, 65, 69, 74, 85, 87, 94, 1027, 1043, 1047, 1067, 1081, 1094, 1142, 1186, 1203, 1205, 1207, 1214, 1227, 1234, 1238, 1241, 1243, 1247, 1261, 1263, 1267, 1285, 1294, 1306, 1322, 1346, 1366