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 A001514 Bessel polynomial {y_n}'(1). (Formerly M4654 N1993) 15
 0, 1, 9, 81, 835, 9990, 137466, 2148139, 37662381, 733015845, 15693217705, 366695853876, 9289111077324, 253623142901401, 7425873460633005, 232122372003909045, 7715943399320562331, 271796943164015920914, 10114041937573463433966 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 REFERENCES J. Riordan, Combinatorial Identities, Wiley, 1968, p. 77. N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS G. C. Greubel, Table of n, a(n) for n = 0..400 N. J. A. Sloane, Letter to J. Riordan, Nov. 1970 FORMULA a(n) = (1/2) * Sum_{k=0..n} (n+k+2)!/((n-k)!*k!*2^k) (with a different offset). D-finite with recurrence: (n-1)^2 * a(n) = (2*n-1)*(n^2 - n + 1)*a(n-1) + n^2*a(n-2). - Vaclav Kotesovec, Jul 22 2015 a(n) ~ 2^(n+1/2) * n^(n+1) / exp(n-1). - Vaclav Kotesovec, Jul 22 2015 a(n) = n*2^n*(1/2)_{n}*hypergeometric1f1(1-n, -2*n, 2), where (a)_{n} is the Pochhammer symbol. - G. C. Greubel, Aug 14 2017 From G. C. Greubel, Aug 16 2017: (Start) G.f.: (1/(1-t))*hypergeometric2f0(2, 3/2; -; 2*t/(1-t)^2). E.g.f.: (1 - 2*x)^(-3/2)*((1 - x)*sqrt(1 - 2*x) + (3*x - 1))*exp((1 - sqrt(1 - 2*x))). (End) MAPLE (As in A001497 define:) f := proc(n) option remember; if n <=1 then (1+x)^n else expand((2*n-1)*x*f(n-1)+f(n-2)); fi; end; [seq( subs(x=1, diff(f(n), x)), n=0..60)]; f2:=proc(n) local k; add((n+k+2)!/((n-k)!*k!*2^k), k=0..n); end; [seq(f2(n), n=0..60)]; # uses a different offset MATHEMATICA Table[Sum[(n+k+1)!/((n-k-1)!*k!*2^(k+1)), {k, 0, n-1}], {n, 0, 20}] (* Vaclav Kotesovec, Jul 22 2015 *) Join[{0}, Table[n*Pochhammer[1/2, n]*2^n* Hypergeometric1F1[1 - n, -2*n, 2], {n, 1, 50}]] (* G. C. Greubel, Aug 14 2017 *) PROG (PARI) for(n=0, 50, print1(sum(k=0, n-1, (n+k+1)!/((n-k-1)!*k!*2^(k+1))), ", ")) \\ G. C. Greubel, Aug 14 2017 CROSSREFS Cf. A001515, A001516, A001518, A065920, A144505. Sequence in context: A199689 A181581 A137062 * A077364 A067478 A077486 Adjacent sequences:  A001511 A001512 A001513 * A001515 A001516 A001517 KEYWORD nonn AUTHOR STATUS approved

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Last modified January 20 17:57 EST 2021. Contains 340308 sequences. (Running on oeis4.)