A379280
G.f. A(x) satisfies A(x) = ( (1 + x*A(x)^3) * (1 + x*A(x)) )^2.
Original entry on oeis.org
1, 4, 38, 500, 7601, 125520, 2187736, 39608616, 737651032, 14040612502, 271931510448, 5341639974490, 106167131932708, 2131125360950758, 43142742495766252, 879810600033569754, 18057207334571432048, 372701480245014988624, 7731178967720860156743
Offset: 0
-
a(n) = sum(k=0, n, binomial(2*n+4*k+2, k)*binomial(2*n+4*k+2, n-k)/(n+2*k+1));
A379282
G.f. A(x) satisfies A(x) = 1/( (1 - x*A(x)^2) * (1 - x*A(x)) )^2.
Original entry on oeis.org
1, 4, 34, 376, 4743, 64710, 929906, 13865206, 212509079, 3327383632, 52994140217, 855842582128, 13982509284464, 230686414552016, 3837897905208588, 64314848237403878, 1084624929809399857, 18393856772155371200, 313487249756740510907, 5366521088581773011788
Offset: 0
-
a(n) = 2*sum(k=0, n, binomial(2*n+3*k+2, k)*binomial(3*n+k+1, n-k)/(2*n+3*k+2));
A379281
G.f. A(x) satisfies A(x) = 1/( (1 - x) * (1 - x*A(x)) )^2.
Original entry on oeis.org
1, 4, 18, 96, 575, 3706, 25078, 175666, 1262723, 9261018, 69024147, 521281642, 3980391050, 30678331440, 238350850248, 1864751821958, 14678131286357, 116160233811868, 923684828888152, 7376541052964806, 59137050311947284, 475757909357776656, 3839678158239147611
Offset: 0
-
a(n) = 2*sum(k=0, n, binomial(2*n-k+2, k)*binomial(3*n-3*k+1, n-k)/(2*n-k+2));
Showing 1-3 of 3 results.