A369007 - OEIS

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A369007

Numbers k for which k' / gcd(k,k') is a multiple of 27, where k' stands for the arithmetic derivative of k, A003415(k).

1, 158, 160, 208, 212, 275, 329, 374, 410, 428, 473, 482, 515, 533, 629, 698, 700, 707, 713, 785, 910, 914, 952, 1055, 1058, 1067, 1072, 1076, 1078, 1080, 1183, 1204, 1238, 1346, 1404, 1431, 1445, 1454, 1490, 1562, 1661, 1691, 1724, 1813, 1841, 1865, 1888, 1937, 1994, 2102, 2219, 2291, 2320, 2372, 2426, 2432, 2570

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OFFSET

1,2

COMMENTS

Question: What is the asymptotic density of these terms? 0.0253...?

A multiplicative semigroup: if m and n are in the sequence, then so is m*n. - Antti Karttunen, Nov 11 2024

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..20000

FORMULA

For all n >= 1, A007949(a(n)) = 3*k, for k >= 0. - Antti Karttunen, Nov 12 2024

PROG

(PARI)