A307002 Numbers > 1 not of the form (3n*k - A319929(n,k))/2 where n and k > 1.

2, 3, 4, 5, 7, 9, 10, 13, 15, 17, 21, 22, 23, 25, 29, 31, 34, 37, 39, 41, 45, 46, 49, 53, 55, 57, 58, 63, 65, 69, 71, 73, 77, 79, 81, 82, 85, 93, 94, 95, 97, 101, 105, 106, 109, 111, 118, 119, 121, 125, 129, 133, 135, 137, 141, 142, 143, 149, 151, 153, 157

Offset: 1

Author

David Lovler, Mar 19 2019

Keywords

• nonn
• easy

Comments

All even terms > 2 appear to be semiprimes of the form 6m+4 (A112774).

The subsequence of odd terms is A307001. - David Lovler, Jan 17 2022

Links

• David Lovler, Table of n, a(n) for n = 1..4399

Crossrefs

Cf. A112774, A307001, A322630, A322744, A340746, A340747.

Third row of array A327263.

Programs

PARI

T319929(n, k) = if (n%2, if (k%2, n+k-1, k), if (k%2, n, 0));
T(n, k) = (3*n*k - T319929(n, k))/2; \\ A322744
lista(nn) = {my(list = List()); for (n=2, nn, for (k=2, nn\n, listput(list, T(n, k)););); setminus([2..nn], Set(list));} \\ Michel Marcus, Jan 24 2021

Extensions

Name amended by David Lovler, Jan 25 2022