# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a035023 Showing 1-1 of 1 %I A035023 #39 Oct 20 2022 03:34:24 %S A035023 1,18,486,17496,787320,42515280,2678462640,192849310080, %T A035023 15620794116480,1405871470483200,139181275577836800, %U A035023 15031577762406374400,1758694598201545804800,221595519373394771404800,29915395115408294139648000,4307816896618794356109312000 %N A035023 One ninth of 9-factorial numbers. %C A035023 E.g.f. is g.f. for A001019(n-1) (powers of nine). %H A035023 G. C. Greubel, Table of n, a(n) for n = 1..325 %H A035023 Index entries for sequences related to factorial numbers. %F A035023 9*a(n) = (9*n)(!^9) = Product_{j=1..n} 9*j = 9^n*n!. %F A035023 E.g.f.: (-1+1/(1-9*x))/9. %F A035023 D-finite with recurrence: a(n) - 9*n*a(n-1) = 0. - _R. J. Mathar_, Jan 28 2020 %F A035023 From _Amiram Eldar_, Jan 08 2022: (Start) %F A035023 Sum_{n>=1} 1/a(n) = 9*(exp(1/9)-1). %F A035023 Sum_{n>=1} (-1)^(n+1)/a(n) = 9*(1-exp(-1/9)). (End) %F A035023 From _G. C. Greubel_, Oct 19 2022: (Start) %F A035023 a(n) = A001019(n-1) * A000142(n). - _G. C. Greubel_, Oct 19 2022 %t A035023 With[{nn=20},Rest[CoefficientList[Series[(-1+1/(1-9*x))/9,{x,0,nn}],x] Range[ 0,nn]!]] (* _Harvey P. Dale_, Apr 07 2019 *) %t A035023 Table[9^(n-1)*n!, {n, 40}] (* _G. C. Greubel_, Oct 19 2022 *) %o A035023 (Magma) [9^(n-1)*Factorial(n): n in [1..40]]; // _G. C. Greubel_, Oct 19 2022 %o A035023 (SageMath) [9^(n-1)*factorial(n) for n in range(1,40)] # _G. C. Greubel_, Oct 19 2022 %Y A035023 Cf. A000142, A007559, A001019, A034171, A035012, A035013. %Y A035023 Cf. A035017, A035018, A035020, A035021, A035022, A045756. %K A035023 easy,nonn %O A035023 1,2 %A A035023 _Wolfdieter Lang_ # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE