A380450 Odd numbers k such that A339792(k^2) = 0, where A339792 is the third coefficient of the lindep transform of sigma.

1, 693, 1463, 1881, 2379, 4389, 11895, 13167, 16653, 25641, 26169, 37271, 40443, 45201, 54717, 57057, 59475, 64233, 65835, 75777, 78507, 100947, 107415, 109725, 111813, 169959, 171171, 183183, 185801, 218085, 223839, 230763, 238887, 250173, 291555, 302841, 316407, 329175, 368745, 380737, 381843, 383019, 392535

Offset

1,2

Comments

Not all odd terms of A322154 appear in this sequence, although most of them do. On the other hand, terms occurring here but not included in A322154 include 1, 59475, 64233, 75777, 100947, 107415, 383019, etc.

Links

Antti Karttunen, Table of n, a(n) for n = 1..1000

Index entries for sequences related to sigma(n).

Formula

a(n) = A000196(A380449(n)).

Prog

(PARI)
A339792(n) = { my(v=lindep([sigma(n), n, 1])); (v*sign(v[1]))[3]; };
A380445(n) = !A339792(n);
is_A380450(n) = ((n%2) && A380445(n^2));

Crossrefs

Square roots of A380449.

Cf. A000196, A322154, A339790, A339791, A339792, A380445.

Sequence in context: A004241 A380444 A322154 * A129913 A031946 A049356

Adjacent sequences: A380447 A380448 A380449 * A380451 A380452 A380453

Keyword

nonn,new

Author

Antti Karttunen, Jan 25 2025

Status

approved