A286283 a(n) = floor(7*n^2/48).

0, 0, 0, 1, 2, 3, 5, 7, 9, 11, 14, 17, 21, 24, 28, 32, 37, 42, 47, 52, 58, 64, 70, 77, 84, 91, 98, 106, 114, 122, 131, 140, 149, 158, 168, 178, 189, 199, 210, 221, 233, 245, 257, 269, 282, 295, 308, 322, 336, 350, 364, 379, 394, 409, 425, 441, 457, 473, 490, 507, 525, 542, 560, 578, 597

Offset: 0

Author

N. J. A. Sloane, May 12 2017

Keywords

• nonn
• easy

Comments

A possible formula for, or lower bound on, or at least a benchmark for, A250000.

Links

• Colin Barker, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (2, -2, 2, -1, 0, 1, -2, 2, -2, 1, 0, -1, 2, -2, 2, -1, 0, 1, -2, 2, -2, 1).

Crossrefs

Cf. A250000.

Programs

Mathematica

Table[Floor[7 n^2/48], {n, 0, 64}] (* Michael De Vlieger, May 22 2017 *)

Formula

G.f.: x^3*(1 + x^2 + x^3 + x^5 - x^6 + x^7 - x^8 + x^9 - x^10 + x^11 + x^13 + x^14 + x^16) / ((1 - x)^3*(1 + x)*(1 - x + x^2)*(1 + x^2)*(1 + x + x^2)*(1 + x^4)*(1 - x^4 + x^8)). - Colin Barker, May 22 2017