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Search: id:A061602
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| A061602 |
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Sum of factorials of the digits of n. |
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+0
15
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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; listen)
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OFFSET
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0,3
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COMMENT
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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
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Harry J. Smith, Table of n, a(n) for n=0,...,1000
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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
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a(24) = (2!) + (4!) = 2 + 24 = 26.
a(153)=127 because 1!+5!+3!=1+120+6=127
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MATHEMATICA
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a[n_] := Total[IntegerDigits[n]! ]; Table[a[n], {n, 1, 53}] - Saif Hakim (saif7463(AT)gmail.com), Apr 23 2006
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PROGRAM
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(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]
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CROSSREFS
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Cf. A061603.
Adjacent sequences: A061599 A061600 A061601 this_sequence A061603 A061604 A061605
Sequence in context: A072132 A066459 A071937 this_sequence A033647 A109834 A131451
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KEYWORD
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nonn,base,easy
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), May 19 2001
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EXTENSIONS
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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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