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 A065944 Bessel polynomial {y_n}''(-1). 2
 0, 0, 6, -60, 720, -9870, 153510, -2679264, 51934680, -1107917910, 25807660560, -651977992380, 17758547202396, -518856566089680, 16188283372489410, -537210169663283760, 18894951642157260480, -702160022681408982114 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 REFERENCES J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77. LINKS G. C. Greubel, Table of n, a(n) for n = 0..400 FORMULA Recurrence: (n-2)*(n-1)*a(n) = -(n-2)*(n+1)*(2*n-1)*a(n-1) + n*(n+1)*a(n-2). - Vaclav Kotesovec, Jul 22 2015 a(n) ~ (-1)^n * 2^(n+1/2) * n^(n+2) / exp(n+1). - Vaclav Kotesovec, Jul 22 2015 From G. C. Greubel, Aug 14 2017: (Start) a(n) = 2*n*(n-1)*(1/2)_{n}*(-2)^(n - 1)* hypergeometric1f1(2 - n, -2*n, -2), where (a)_{n} is the Pochhammer symbol. E.g.f.: (1 + 2*x)^(-5/2)*(x*(x + 2)*sqrt(1 + 2*x) + (2*x^3 - 2*x)) * exp(-1 + sqrt(1 + 2*x)). (End) G.f.: (6*x^2/(1-x)^5)*hypergeometric2f0(3,5/2; - ; -2*x/(1-x)^2). - G. C. Greubel, Aug 16 2017 MATHEMATICA Table[Sum[(n+k+2)!*(-1)^k/(2^(k+2)*(n-k-2)!*k!), {k, 0, n-2}], {n, 0, 20}] (* Vaclav Kotesovec, Jul 22 2015 *) Join[{0, 0}, Table[4*n*(n-1)*Pochhammer[1/2, n]*(-2)^(n-2)* Hypergeometric1F1[2-n, -2*n, -2], {n, 2, 20}]] (* G. C. Greubel, Aug 14 2017 *) PROG (PARI) for(n=0, 20, print1(sum(k=0, n-2, (n+k+2)!*(-1)^k/(2^(k+2)*(n-k-2)!*k!)), ", ")) \\ G. C. Greubel, Aug 14 2017 (MAGMA) f:=Factorial; [0, 0] cat [(&+[((-1)^k*f(n+k+2)/(2^(k+2)*f(n-k-2) *f(k))): k in [0..n-2]]): n in [2..20]]; // G. C. Greubel, Jul 10 2019 (Sage) f=factorial; [0, 0]+[sum((-1)^k*f(n+k+2)/(2^(k+2)*f(n-k-2)*f(k)) for k in (0..n-2)) for n in (2..20)] # G. C. Greubel, Jul 10 2019 (GAP) f:=Factorial;; Concatenation([0, 0], List([2..20], n-> Sum([0..n-2], k-> (-1)^k*f(n+k+2)/(2^(k+2)*f(n-k-2)*f(k)) ))); # G. C. Greubel, Jul 10 2019 CROSSREFS Cf. A001518, A001516. Sequence in context: A086984 A000894 A112117 * A126779 A218441 A120973 Adjacent sequences:  A065941 A065942 A065943 * A065945 A065946 A065947 KEYWORD sign AUTHOR N. J. A. Sloane, Dec 08 2001 STATUS approved

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Last modified February 22 12:42 EST 2020. Contains 332136 sequences. (Running on oeis4.)