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A259162

Positive hexagonal numbers (A000384) that are pentagonal numbers (A000326) divided by 2.

6, 58311, 559902916, 5376187741821, 51622154137063026, 495675918647891434531, 4759480119234899417304336, 45700527609217585557064800441, 438816461344227137284036796530846, 4213515616126741362983735763224383551, 40458176507232509223142693514443734326556

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OFFSET

1,1

COMMENTS

Intersection of A000384 and A193866 (even pentagonal numbers divided by 2). - Michel Marcus, Jun 20 2015

LINKS

Colin Barker, Table of n, a(n) for n = 1..251

Index entries for linear recurrences with constant coefficients, signature (9603,-9603,1).

FORMULA

G.f.: -x*(x^2+693*x+6) / ((x-1)*(x^2-9602*x+1)).

EXAMPLE

6 is in the sequence because 6 is the 2nd hexagonal number, and 2*6 is the 3rd pentagonal number.