A388025 Primitive terms of A388022: numbers k that satisfy sigma(k) AND 3*k = 3*k, but none of whose proper divisors satisfy the same condition.

120, 672, 2352, 5220, 5616, 7344, 10296, 10944, 14256, 16416, 17100, 26496, 26820, 32472, 48312, 62820, 68112, 70020, 91620, 91872, 93024, 97152, 98736, 98820, 103968, 110340, 111456, 145600, 164016, 183168, 186912, 192096, 199620, 200376, 220176, 220704, 228528, 229860, 247140, 288864, 295776, 300420, 319536, 328536

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..4461

Index entries for sequences related to binary expansion of n.

Index entries for sequences related to sigma(n).

Prog

(PARI)
is_A388022(n) = (bitand(sigma(n), 3*n)==3*n);
is_A388025(n) = if(!is_A388022(n), 0, fordiv(n, d, if(d<n && is_A388022(d), return(0))); (1));

Crossrefs

Subsequence of A388022.

Cf. A000203, A004198.

Cf. A005820 (subsequence).

Cf. also A388019.

Sequence in context: A386010 A385749 A292365 * A306373 A356548 A113546

Adjacent sequences: A388022 A388023 A388024 * A388026 A388027 A388028

Keyword

nonn

Author

Antti Karttunen, Sep 15 2025

Status

approved