A011879 a(n) = floor( n(n-1)/26 ).

0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 16, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 38, 40, 43, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 76, 79, 83, 86, 90, 94, 98, 102, 106, 110, 114, 118, 122, 127, 131, 136, 140, 145

Offset

0,9

Links

G. C. Greubel, Table of n, a(n) for n = 0..300

Index entries for linear recurrences with constant coefficients, signature (2, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -2, 1).

Formula

G.f.: (x^6 (1+x (-1+x (1+(-1+x) x))))/(1+x (-2+x (1+x^11 (-1+(2-x) x)))). - Peter J. C. Moses, Jun 01 2014

a(n)= +2*a(n-1) -a(n-2) +a(n-13) -2*a(n-14) +a(n-15). - R. J. Mathar, Aug 11 2021

Mathematica

Table[Floor[n(n-1)/26], {n, 0, 600}] (* G. C. Greubel, Sep 03 2015 *)
Join[{0}, Floor[#/13]&/@Accumulate[Range[0, 70]]] (* Harvey P. Dale, Apr 26 2020 *)

Prog

(PARI) a(n) = n*(n-1)\26; \\ G. C. Greubel, Sep 03 2015

Crossrefs

Sequence in context: A273662 A034138 A254667 * A011878 A017896 A118868

Adjacent sequences: A011876 A011877 A011878 * A011880 A011881 A011882

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved