Search: id:A061602
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%I A061602
%S A061602 1,1,2,6,24,120,720,5040,40320,362880,2,2,3,7,25,121,721,5041,40321,
%T A061602 362881,3,3,4,8,26,122,722,5042,40322,362882,7,7,8,12,30,126,726,5046,
%U A061602 40326,362886,25,25,26,30,48,144,744,5064,40344,362904,121,121,122,126
%N A061602 Sum of factorials of the digits of n.
%C A061602 Numbers n such that a(n)=n are known as factorions. It is known that 
               there are exactly four of these: 1, 2, 145, 40585.
%H A061602 Harry J. Smith, <a href="b061602.txt">Table of n, a(n) for n=0,...,1000</
               a>
%H A061602 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Factorion.html">Link to a section of The World of Mathematics.</a>
%H A061602 Project Euler Problem 74: <a href="http://projecteuler.net/index.php?section=problems&id=74"> 
               Determine the number of factorial chains that contain exactly sixty 
               non-repeating terms. </a> [From Dremov Dmitry (dremovd(AT)gmail.com), 
               May 21 2009]
%e A061602 a(24) = (2!) + (4!) = 2 + 24 = 26.
%e A061602 a(153)=127 because 1!+5!+3!=1+120+6=127
%t A061602 a[n_] := Total[IntegerDigits[n]! ]; Table[a[n], {n, 1, 53}] - Saif Hakim 
               (saif7463(AT)gmail.com), Apr 23 2006
%o A061602 (PARI) { for (n=0, 1000, a=0; x=n; until (x==0, a+=(x - 10*(x\10))!; 
               x=x\10); write("b061602.txt", n, " ", a) ) } [From Harry J. Smith 
               (hjsmithh(AT)sbcglobal.net), Jul 25 2009]
%Y A061602 Cf. A061603.
%Y A061602 Sequence in context: A072132 A066459 A071937 this_sequence A033647 A109834 
               A131451
%Y A061602 Adjacent sequences: A061599 A061600 A061601 this_sequence A061603 A061604 
               A061605
%K A061602 nonn,base,easy
%O A061602 0,3
%A A061602 Amarnath Murthy (amarnath_murthy(AT)yahoo.com), May 19 2001
%E A061602 Corrected and extended by Vladeta Jovovic (vladeta(AT)eunet.rs), May 
               19 2001. Link and amended comment by Mark Hudson (mrmarkhudson(AT)hotmail.com), 
               Nov 12 2004.

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