A324814 Numbers n > 1 for which sigma(A156552(n)) == 2 (mod 4).

6, 14, 15, 18, 33, 35, 38, 42, 54, 58, 65, 69, 70, 75, 77, 90, 93, 102, 106, 110, 119, 130, 143, 145, 150, 162, 165, 174, 177, 185, 190, 209, 217, 221, 230, 231, 234, 242, 245, 273, 285, 287, 290, 294, 299, 305, 323, 330, 338, 350, 357, 375, 378, 390, 407, 410, 414, 434, 437, 450, 455, 465, 469, 473, 483, 493, 494, 507

Offset: 1

Author

Antti Karttunen, Mar 16 2019

Keywords

• nonn

Comments

Sequence A005940(1+A191217(n)), n >= 1, sorted into ascending order.

Links

• Index entries for sequences related to binary expansion of n
• Index entries for sequences computed from indices in prime factorization
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A005940, A191217, A324812, A324813, A324824 (characteristic function).

Programs

PARI

A156552(n) = {my(f = factor(n), p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res}; \\ From A156552 by David A. Corneth
A324824(n) = ((n>1)&&(2==(sigma(A156552(n))%4)));
A324824(n) = (2==(A323243(n)%4)); \\ Alternatively.
for(n=1,oo,if(A324824(n),print1(n,", ")));