A326917 Nonnegative numbers of the form 8*T(x) - T(y) with 0 <= x, 0 <= y, where T() denotes a triangular number.

0, 2, 3, 5, 7, 8, 9, 12, 14, 15, 18, 20, 21, 23, 24, 25, 27, 29, 32, 33, 34, 35, 38, 42, 44, 45, 47, 48, 52, 53, 54, 57, 59, 60, 62, 63, 65, 70, 71, 74, 75, 77, 78, 79, 80, 84, 88, 89, 90, 92, 93, 96, 98, 99, 102, 104, 105, 107, 110, 113, 114, 115, 117, 119

Offset

1,2

Comments

When incremented by 1 this is also the difference between an odd square (1 + 8*T) and a triangular number T.

Links

Table of n, a(n) for n=1..64.

Formula

a(n) = A175035(n) - 1.

Example

8*A000217(1) - A000217(2) = 8*1 - 3 = 5 = a(4).

Mathematica

T[n_] := n (n + 1)/2; Select[Union[Flatten[Table[8 T[x] - T[y], {x, 0, 15}, {y, 0, 100}]]], 115 >= # >= 0 &]

Crossrefs

Cf. A000217 (T), A175035, A016754 (odd squares).

Sequence in context: A344591 A049468 A187332 * A001857 A091532 A108345

Adjacent sequences: A326914 A326915 A326916 * A326918 A326919 A326920

Keyword

nonn

Author

Ralf Steiner, Oct 21 2019

Status

approved