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A061602
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Sum of factorials of the digits of n.
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21
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1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 2, 2, 3, 7, 25, 121, 721, 5041, 40321, 362881, 3, 3, 4, 8, 26, 122, 722, 5042, 40322, 362882, 7, 7, 8, 12, 30, 126, 726, 5046, 40326, 362886, 25, 25, 26, 30, 48, 144, 744, 5064, 40344, 362904, 121, 121, 122, 126
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| 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.
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LINKS
| Harry J. Smith, Table of n, a(n) for n=0,...,1000
Eric Weisstein's World of Mathematics, Factorion.
Project Euler Problem 74: Determine the number of factorial chains that contain exactly sixty non-repeating terms. [From Dremov Dmitry (dremovd(AT)gmail.com), May 21 2009]
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EXAMPLE
| a(24) = (2!) + (4!) = 2 + 24 = 26.
a(153)=127 because 1!+5!+3!=1+120+6=127
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MAPLE
| A061602 := proc(n)
add(factorial(d), d=convert(n, base, 10)) ;
end proc: # R. J. Mathar, Dec 18 2011
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MATHEMATICA
| a[n_] := Total[IntegerDigits[n]! ]; Table[a[n], {n, 1, 53}] - Saif Hakim (saif7463(AT)gmail.com), Apr 23 2006
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PROG
| (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]
(MAGMA) a061602:=func< n | n eq 0 select 1 else &+[ Factorial(d): d in Intseq(n) ] >; [ a061602(n): n in [0..60] ];
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CROSSREFS
| Cf. A061603.
Sequence in context: A072132 A066459 A071937 * A033647 A109834 A131451
Adjacent sequences: A061599 A061600 A061601 * A061603 A061604 A061605
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KEYWORD
| nonn,base,easy
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), May 19 2001
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EXTENSIONS
| 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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