Expansion of g.f.: (1+x^2)*(1+2*x^2)*(1+3*x^2)/(1-4*x+6*x^2-18*x^3 +11*x^4-22*x^5+6*x^6-6*x^7).

A123893

Expansion of g.f.: (1+x^2)*(1+2*x^2)*(1+3*x^2)/(1-4*x+6*x^2-18*x^3 +11*x^4-22*x^5+6*x^6-6*x^7).

Terms

    a(0) =1a(1) =4a(2) =16a(3) =58a(4) =208a(5) =750a(6) =2708a(7) =9772a(8) =35256a(9) =127210a(10) =459012a(11) =1656228a(12) =5976040a(13) =21562946a(14) =77804232a(15) =280736004a(16) =1012961416a(17) =3655002994a(18) =13188110940a(19) =47585806908a(20) =171700784680a(21) =619536821778

External references