A351562 Odd composites k such that A342926(2*k) is a multiple of 3.

15, 33, 45, 51, 69, 87, 99, 105, 123, 135, 141, 147, 153, 159, 165, 175, 177, 195, 207, 213, 231, 249, 255, 261, 267, 285, 297, 303, 315, 321, 325, 339, 345, 357, 369, 375, 393, 405, 411, 423, 429, 435, 441, 447, 459, 465, 475, 477, 483, 495, 501, 507, 519, 531, 537, 555, 561, 573, 585, 591, 609, 615, 621, 627, 639

Offset

1,1

Links

Table of n, a(n) for n=1..65.

Index entries for sequences related to sigma(n)

Prog

(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A342926(n) = (A003415(sigma(n))-n);
isA351562(n) = ((n%2)&&!isprime(n)&&!(A342926(2*n)%3));

Crossrefs

Cf. A000203, A003415, A342925, A342926, A347880.

Cf. A347874 (the intersection of this sequence and A347872).

Sequence in context: A246755 A212311 A262741 * A316153 A190754 A357934

Adjacent sequences: A351559 A351560 A351561 * A351563 A351564 A351565

Keyword

nonn

Author

Antti Karttunen, Feb 23 2022

Status

approved