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A351562
Odd composites k such that A342926(2*k) is a multiple of 3.
1
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
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. A347874 (the intersection of this sequence and A347872).
Sequence in context: A246755 A212311 A262741 * A316153 A190754 A357934
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 23 2022
STATUS
approved