A373259 - OEIS

A373259

Numbers k such that k' / gcd(k,k') is a multiple of 4 and A276085(k) is a multiple of 8, where k' stands for the arithmetic derivative of k, A003415, and A276085 is the primorial base log-function.

1, 15, 28, 39, 51, 55, 76, 81, 87, 115, 124, 143, 144, 183, 187, 188, 215, 219, 225, 256, 259, 267, 268, 287, 291, 295, 297, 299, 303, 316, 319, 327, 339, 355, 371, 391, 400, 411, 412, 415, 420, 441, 471, 508, 519, 528, 535, 556, 559, 579, 585, 591, 621, 625, 652, 655, 667, 671, 687, 699, 703, 716, 731, 755, 765, 767

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OFFSET

1,2

COMMENTS

This is a multiplicative semigroup; if m and n are in the sequence then so is m*n.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

PROG

(PARI) isA373259 = A373258;

CROSSREFS

Intersection of A369005 and A373138.

Subsequence of A369002.