A011875 Floor( n*(n-1)/22 ).

0, 0, 0, 0, 0, 0, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 34, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 67, 70, 74, 78, 82, 86, 90, 94, 98, 102, 106, 111, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 166, 171, 177, 183, 189, 195, 201, 207

Offset

0,9

Links

Table of n, a(n) for n=0..68.

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

Formula

a(n) = +2*a(n-1) -a(n-2) +a(n-11) -2*a(n-12) +a(n-13). G.f.: x^6*(x^2-x+1) / ((1-x)^3*(1+x^10+x^9+x^8+x^7+x^6+x^5+x^4+x^3+x^2+x) ). [R. J. Mathar, Apr 15 2010]

Mathematica

Table[Floor[(n(n-1))/22], {n, 0, 70}] (* or *) LinearRecurrence[{2, -1, 0, 0, 0, 0, 0, 0, 0, 0, 1, -2, 1}, {0, 0, 0, 0, 0, 0, 1, 1, 2, 3, 4, 5, 6}, 70]

Crossrefs

Sequence in context: A093668 A026501 A000926 * A249575 A053433 A091401

Adjacent sequences: A011872 A011873 A011874 * A011876 A011877 A011878

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved