A386550 - OEIS

A386550

Indices of hexagonal numbers that are six times another hexagonal number.

0, 2, 176, 17222, 1687556, 165363242, 16203910136, 1587817830062, 155589943435916, 15246226638889682, 1493974620667752896, 146394266598800894102, 14345144152061819869076, 1405677732635459546275322, 137742072654122973715112456, 13497317442371415964534745342

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..16.

Index entries for linear recurrences with constant coefficients, signature (99,-99,1).

FORMULA

a(n) = (3*A269551(n-2) - 7)/4 for n>=2. - Hugo Pfoertner, Jul 26 2025

G.f.: 2*x^2*(1 - 11*x - 2*x^2)/((1 - x)*(1 - 98*x + x^2)). - Stefano Spezia, Jul 27 2025

EXAMPLE

176 is in this sequence because the 176th hexagonal number (61776) is six times another hexagonal number.

CROSSREFS