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A259159 Positive squares (A000290) that are heptagonal numbers (A000566) divided by 2. 3
9, 938961, 97353360225, 10093791093915321, 1046544448101974957529, 108507821458015176452612289, 11250307943363385076857772396401, 1166454428075294670080752381151042025, 120940328000452394039949183305644566845481 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Colin Barker, Table of n, a(n) for n = 1..200

Index entries for linear recurrences with constant coefficients, signature (103683,-103683,1).

FORMULA

G.f.: -9*x*(x^2+646*x+1) / ((x-1)*(x^2-103682*x+1)).

EXAMPLE

9 is in the sequence because 9 is the 3rd square, and 2*9 is the 3rd heptagonal number.

MATHEMATICA

LinearRecurrence[{103683, -103683, 1}, {9, 938961, 97353360225}, 20] (* Vincenzo Librandi, Jun 20 2015 *)

PROG

(PARI) Vec(-9*x*(x^2+646*x+1)/((x-1)*(x^2-103682*x+1)) + O(x^20))

CROSSREFS

Cf. A000290, A000566, A259156-A259158, A259160-A259167.

Sequence in context: A013850 A174001 A273234 * A340181 A131678 A229687

Adjacent sequences:  A259156 A259157 A259158 * A259160 A259161 A259162

KEYWORD

nonn,easy

AUTHOR

Colin Barker, Jun 19 2015

STATUS

approved

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Last modified August 11 08:17 EDT 2022. Contains 356055 sequences. (Running on oeis4.)