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Search: id:A055493
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| A055493 |
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Numbers n such that Sum_{k=1..n} k! - 2 is prime. |
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+0
1
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| 3, 4, 5, 12, 13, 19, 65, 90, 123, 211, 281, 459
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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There are no further terms in this sequence because for all n >= 466 (Sum_{k=1..n} k!) - 2 is divisible by 467. [From Dmitry Kamenetsky (dkamen(AT)rsise.anu.edu.au), Feb 10 2009]
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EXAMPLE
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1! + 2! + 3! + 4! + 5! -2 = 1 + 2 + 6 + 24 + 120 - 2 = 151 which is a prime.
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MATHEMATICA
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Do[If[PrimeQ[Sum[m!, {m, 1, n}]-2], Print[n]], {n, 1, 2500}]
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CROSSREFS
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Sequence in context: A074221 A052276 A046964 this_sequence A109350 A077034 A076601
Adjacent sequences: A055490 A055491 A055492 this_sequence A055494 A055495 A055496
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KEYWORD
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nonn,fini,full
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 05 2000
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