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Search: id:A119556
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| A119556 |
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Primes in the sequence a(n+1)=a(n)+[(-1)^(n+1)]*n!, with a(0)=0. |
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+0
1
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| 5, 101, 4421, 1226280710981, 115578717622022981, 32656499591185747972776747396512425885838364422981, 13637238560507943224811827029784398731973085968949065951959304510863783836442298\ 1
(list; graph; listen)
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OFFSET
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0,1
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FORMULA
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a(n+1)=a(n)+[(-1)^(n+1)]*n!, with a(0)=0
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EXAMPLE
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a(0)=0
a(1)=0 + [(-1)^2]*1! = 0 + 1 = 1
a(2)=1 + [(-1)^3]*2! = 1 - 2 = -1
a(3)=-1 +[(-1)^4]*3! = -1 + 6 = 5 that is prime
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MAPLE
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P:=proc(n) local i, j; j:=0; for i from 1 by 1 to n do j:=j+((-1)^(i+1))*i!; if isprime(j) then print(i); fi; od; end: P(100);
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CROSSREFS
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Sequence in context: A041187 A074790 A009757 this_sequence A009765 A113073 A057207
Adjacent sequences: A119553 A119554 A119555 this_sequence A119557 A119558 A119559
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KEYWORD
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easy,nonn
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AUTHOR
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Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), May 30 2006
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