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A253716 Hexagonal numbers (A000384) which are also centered heptagonal numbers (A069099). 3
1, 16322041, 4145734153, 67933251842771953, 17254778510170993681, 282742011610770921096804841, 71815357774355276244995175961, 1176788140728629029198108610250463201, 298899554649081431834808455098428958753, 4897858370145334123819452782766901335994312153 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Colin Barker, Table of n, a(n) for n = 1..208

Index entries for linear recurrences with constant coefficients, signature (0,4162056194,0,-1).

FORMULA

a(n) = 4162056194*a(n-2)-a(n-4).

G.f.: -x*(x-1)*(x^2+16322042*x+1) / ((x^2-64514*x+1)*(x^2+64514*x+1)).

EXAMPLE

16322041 is in the sequence because it is the 2857th hexagonal number and the 2160th centered heptagonal number.

MATHEMATICA

LinearRecurrence[{0, 4162056194, 0, -1}, {1, 16322041, 4145734153, 67933251842771953}, 20] (* Harvey P. Dale, Jan 05 2017 *)

PROG

(PARI) Vec(-x*(x-1)*(x^2+16322042*x+1)/((x^2-64514*x+1)*(x^2+64514*x+1)) + O(x^100))

CROSSREFS

Cf. A000384, A069099, A253714, A253715.

Sequence in context: A105650 A234457 A204604 * A216004 A155949 A192203

Adjacent sequences:  A253713 A253714 A253715 * A253717 A253718 A253719

KEYWORD

nonn,easy

AUTHOR

Colin Barker, Jan 10 2015

STATUS

approved

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Last modified March 5 16:55 EST 2021. Contains 341827 sequences. (Running on oeis4.)