A332227 Odd numbers k such that sigma(k) is congruent to 2 modulo 8.

17, 41, 73, 89, 97, 113, 137, 153, 193, 233, 241, 257, 281, 313, 325, 337, 353, 369, 401, 409, 433, 449, 457, 521, 569, 577, 593, 601, 617, 641, 657, 673, 725, 761, 769, 801, 809, 833, 845, 857, 873, 881, 925, 929, 937, 953, 977, 1009, 1017, 1033, 1049, 1097, 1129, 1153, 1193, 1201, 1217, 1233, 1249, 1289, 1297, 1321

Offset: 1

Author

Antti Karttunen, Feb 13 2020

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..25000
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203.

Subsequence of A191218 and of A332226.

Cf. A332228 (a subsequence, terms that are not prime powers).

Programs

Mathematica

Select[Range[1,1401,2],Mod[DivisorSigma[1,#],8]==2&] (* Harvey P. Dale, Apr 12 2021 *)

PARI

isA332227(n) = ((n%2)&&2==(sigma(n)%8));