A253514 Centered heptagonal numbers (A069099) which are also centered octagonal numbers (A016754).

1, 841, 755161, 678133681, 608963290321, 546848356574521, 491069215240629481, 440979608437728699361, 395999197307865131396641, 355606838202854450265484201, 319334544706965988473273415801, 286762065540017254794549261905041

Offset

1,2

Links

Colin Barker, Table of n, a(n) for n = 1..339

Index entries for linear recurrences with constant coefficients, signature (899,-899,1).

Formula

a(n) = 899*a(n-1)-899*a(n-2)+a(n-3).

G.f.: -x*(x^2-58*x+1) / ((x-1)*(x^2-898*x+1)).

Example

841 is in the sequence because it is the 16th centered heptagonal number and the 15th centered octagonal number.

Prog

(PARI) Vec(-x*(x^2-58*x+1)/((x-1)*(x^2-898*x+1)) + O(x^100))

Crossrefs

Cf. A016754, A069099, A253446, A253447.

Sequence in context: A361675 A253599 A121499 * A342841 A337730 A049530

Adjacent sequences: A253511 A253512 A253513 * A253515 A253516 A253517

Keyword

nonn,easy

Author

Colin Barker, Jan 03 2015

Status

approved