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 A049388 a(n) = (n+7)!/7!. 25
 1, 8, 72, 720, 7920, 95040, 1235520, 17297280, 259459200, 4151347200, 70572902400, 1270312243200, 24135932620800, 482718652416000, 10137091700736000, 223016017416192000, 5129368400572416000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The asymptotic expansion of the higher order exponential integral E(x,m=1,n=8) ~ exp(-x)/x*(1 - 8/x + 72/x^2 - 720/x^3 + 7920/x^4 - 95040/x^5 + 235520/x^6 - 17297280/x^7 + ...) leads to the sequence given above. See A163931 and A130534 for more information. - Johannes W. Meijer, Oct 20 2009 a(n) = A173333(n+7,7). - Reinhard Zumkeller, Feb 19 2010 a(n) = A245334(n+7,n) / 8. - Reinhard Zumkeller, Aug 31 2014 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..300 FORMULA a(n) = (n+7)!/7!. E.g.f.: 1/(1-x)^8. MATHEMATICA ((Range[0, 20]+7)!)/7! (* Harvey P. Dale, Jul 31 2012 *) PROG (MAGMA) [Factorial(n+7)/5040: n in [0..25]]; // Vincenzo Librandi, Jul 20 2011 (Haskell) a049388 = (flip div 5040) . a000142 . (+ 7) -- Reinhard Zumkeller, Aug 31 2014 (PARI) vector(20, n, n--; (n+7)!/7!) \\ G. C. Greubel, Aug 15 2018 CROSSREFS Cf. A000142, A001710, A001715, A001720, A001725, A001730, A051339. a(n)= A051379(n, 0)*(-1)^n (first unsigned column of triangle). Cf. A245334. Sequence in context: A165323 A082366 A221159 * A014479 A013992 A279156 Adjacent sequences:  A049385 A049386 A049387 * A049389 A049390 A049391 KEYWORD easy,nonn AUTHOR STATUS approved

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Last modified April 19 21:57 EDT 2021. Contains 343117 sequences. (Running on oeis4.)