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Search: id:A119555
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| A119555 |
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Primes in the sequence a(n+1)=a(n)+[(-1)^n]*n!, with a(0)=0. |
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+0
1
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| 19, 619, 35899, 3301819, 468544077492065936712052044718939948687543330546977719976017418129955876663406131164377030450551575840099843957105136480237871017419158043635450756712088769133544426722033165168878328322819566779381528981882285541609256481166622331374702000809600061055686236758821446539362161635577019
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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a(0)=0 a(1)=0 + [(-1)^1]*1! = 0 - 1 = -1 a(2)=-1 + [(-1)^2]*2! = -1 + 2 = 1 a(3)=1 + [(-1)^3]*3! = 1 - 6 = -5 a(4)=-5 + [(-1)^4]*4! = -5 + 24 = 19 that is prime
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FORMULA
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a(n+1)=a(n)+[(-1)^n]*n!, with a(0)=0
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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)*i!; if isprime(j) then print(j); fi; od; end: P(100);
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CROSSREFS
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Adjacent sequences: A119552 A119553 A119554 this_sequence A119556 A119557 A119558
Sequence in context: A012845 A142023 A075879 this_sequence A107118 A078986 A041687
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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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