A369661 - OEIS

A369661

Numbers k whose arithmetic derivative k' is of the form 4m+2, and k' has an even number of prime factors.

9, 21, 25, 33, 49, 57, 69, 85, 93, 121, 129, 133, 145, 169, 177, 205, 213, 217, 237, 249, 253, 265, 289, 309, 329, 361, 375, 393, 417, 445, 459, 469, 473, 489, 493, 505, 517, 529, 533, 553, 565, 573, 581, 597, 629, 633, 669, 685, 697, 713, 753, 781, 783, 793, 813, 817, 819, 841, 865, 869, 875, 889, 913, 933, 949, 961

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OFFSET

1,1

COMMENTS

Equally, numbers k whose arithmetic derivative k' is congruent to 2 modulo 4 and A276085(k') is congruent to 3 modulo 4.

Numbers k such that A003415(k) is in A369966.

For all n >= 1, A003415((1/2)*A003415(a(n))) is odd.

LINKS

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

PROG

(PARI) \\ See A369660.

CROSSREFS