A327260 Odd numbers not of the form 2*n*k - n - k + 1 where n and k are odd numbers > 1.

1, 3, 5, 7, 9, 11, 15, 17, 19, 21, 25, 27, 29, 31, 35, 37, 39, 45, 47, 49, 51, 55, 57, 61, 65, 67, 69, 71, 75, 79, 81, 87, 89, 91, 97, 99, 101, 105, 107, 109, 115, 117, 119, 121, 125, 127, 129, 135, 139, 141, 147, 151, 155, 157, 159, 161, 165, 169

Offset: 1

Author

David Lovler, Aug 27 2019

Keywords

• nonn

Comments

Terms are the odd numbers not appearing in array A327259 with its first row and column omitted.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A307001, A327259, A327261.

Programs

Maple

N:= 201: # for terms <= N
f:= (n,k) -> 2*n*k-n-k+1:
S:= {seq(i,i=1..N,2)} minus {seq(seq(f(n,k),k=3..min(N,(N+n-1)/(2*n-1)),2),n=3..(N+2)/5,2)}:
sort(convert(S,list)); # Robert Israel, Sep 09 2020

Mathematica

Select[2 Range[100]-1, FindInstance[# == 1 + 2*n + k (2 + 8 n) && n>0 && k>0, {n, k}, Integers] === {} &] (* David Lovler, Dec 28 2020 *)

Extensions

Corrected by Robert Israel, Sep 09 2020