OFFSET
1,3
COMMENTS
By construction and recurrence, 30*a(n)^2 + 30*a(n) + 1 = j(n)^2.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
FORMULA
G.f.: x^3*(3*x^2+4*x+3)/((1-x)*(x^4-22*x^2+1)). - Maksym Voznyy (voznyy(AT)mail.ru), Aug 11 2009
MATHEMATICA
Rest[CoefficientList[Series[x^3*(3*x^2+4*x+3)/((1-x)*(x^4-22*x^2+1)), {x, 0, 50}], x]] (* G. C. Greubel, Jul 15 2018 *)
PROG
(PARI) x='x+O('x^30); concat([0, 0], Vec(x^3*(3*x^2+4*x+3)/((1-x)*(x^4-22*x^2+1)))) \\ G. C. Greubel, Jul 15 2018
(Magma) m:=25; R<x>:=PowerSeriesRing(Integers(), m); [0, 0] cat Coefficients(R!(x^3*(3*x^2+4*x+3)/((1-x)*(x^4-22*x^2+1)))); // G. C. Greubel, Jul 15 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Mar 27 2005
EXTENSIONS
Terms a(19) onward added by G. C. Greubel, Jul 15 2018
STATUS
approved