Search: id:A055486
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%I A055486
%S A055486 1,0,1,3,4,15,33,111,382,1195,3366,14077,53265,229603,910254
%N A055486 Number of solutions to Sigma[x] = n!.
%D A055486 R. K. Guy (1981): Unsolved Problems In Number Theory, B39.
%F A055486 a(n) = A054973(n!) = Cardinality[{x; A000203(x) = A000142(n)}]
%e A055486 n = 9, n! = 362880 and the solution set is {97440,...,205634,..,361657} 
               of 382 integers x, so that sigma(x) = 9!, thus a(9) = 382
%p A055486 with(numtheory):for f from 1 to 9 do fac := f!: k := 0:for n from 1 to 
               fac do if sigma(n)=fac then k := k+1: fi: od: print( k); od:
%Y A055486 Cf. A000142, A000203, A054973, A014197, A055488, A055489.
%Y A055486 Sequence in context: A167367 A024858 A135100 this_sequence A041665 A052133 
               A127144
%Y A055486 Adjacent sequences: A055483 A055484 A055485 this_sequence A055487 A055488 
               A055489
%K A055486 more,nonn
%O A055486 1,4
%A A055486 Labos E. (labos(AT)ana.sote.hu), Jun 28 2000
%E A055486 More terms from Jud McCranie (j.mccranie(AT)comcast.net), Oct 09 2000
%E A055486 a(13)-a(14) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 
               22 2008
%E A055486 a(15) from Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 13 2009

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