A179281 - OEIS

A179281

E.g.f. equals the imaginary part of the series F(x) = 1 + x*F(x)^i where i=sqrt(-1).

0, 0, 2, -3, -56, 720, 360, -175770, 2811520, 27714960, -2332820800, 36227931300, 1242856742400, -79410400212000, 881326533651200, 97641790837227000, -5371510570250240000, 7482518858066928000, 12885336165384393984000

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..18.

FORMULA

a(n) = imaginary part of C(i*n,n)/(i*n-n+1).

EXAMPLE

E.g.f.: 2*x^2/2! - 3*x^3/3! - 56*x^4/4! + 720*x^5/5! + 360*x^6/6! + ...

E.g.f. equals the imaginary part of F(x) = 1 + x*F(x)^i where

F(x) = 1 + x + i*x^2 - (3 + i)*x^3/2 + (6 - 7*i)*x^4/3 + (35 + 72*i)*x^5/12 - (31 - i)*x^6/2 + (1043 - 2511*i)*x^7/72 + (4074 + 4393*i)*x^8/63 - (52299 - 17108*i)*x^9/224 + (171324 - 1458013*i)*x^10/2268 + (53576369 + 32934483*i)*x^11/36288 - (1811381 - 1198743*i)*x^12/462 + ...

PROG

(PARI) {a(n)=n!*imag(binomial(I*n, n)/((I-1)*n+1))}

CROSSREFS

Cf. A179281 (real part).

Sequence in context: A371140 A371121 A371227 * A000656 A116052 A141509

Adjacent sequences: A179278 A179279 A179280 * A179282 A179283 A179284

KEYWORD

sign

AUTHOR

Paul D. Hanna, Jul 08 2010

STATUS

approved