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Search: id:A063960
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| A063960 |
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Sum of non-unitary prime divisors of n!: sum of those prime factors for which the exponent exceeds 1. |
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+0
2
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| 0, 0, 0, 2, 2, 5, 5, 5, 5, 10, 10, 10, 10, 17, 17, 17, 17, 17, 17, 17, 17, 28, 28, 28, 28, 41, 41, 41, 41, 41, 41, 41, 41, 58, 58, 58, 58, 77, 77, 77, 77, 77, 77, 77, 77, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 129, 129, 129, 129, 160, 160, 160, 160
(list; graph; listen)
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OFFSET
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1,4
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,1000
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EXAMPLE
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20!=(2^18).(3^8).(5^4).(7^2).11.13.17.19, the non-unitary prime-factors are {2,3,5,7}, with sum=17 so a(20)=17.
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PROGRAM
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(PARI) { for (n=1, 1000, f=factor(n!)~; a=0; for (i=1, length(f), if (f[2, i]>1, a+=f[1, i])); write("b063960.txt", n, " ", a) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 04 2009]
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CROSSREFS
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A056169-A056172, A034444.
Sequence in context: A161622 A116559 A008280 this_sequence A025510 A158106 A069896
Adjacent sequences: A063957 A063958 A063959 this_sequence A063961 A063962 A063963
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Sep 04 2001
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