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A078190
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Primes of the form A004154(n) - 1.
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4
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5, 23, 11, 71, 503, 62270207, 871782911, 121645100408831, 243290200817663, 304888344611713860501503, 137637530912263450463159795815809023
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OFFSET
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1,1
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COMMENTS
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More precisely, scan A004154, subtract 1 and record the answer if it is a prime. The sequence is not monotonic.
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LINKS
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MAPLE
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A004154 := proc(n) option remember ; local m ; if n <= 1 then RETURN(1) ; else m := A004154(n-1)*n ; while m mod 10 = 0 do m := m /10 ; end ; RETURN(m) ; fi ; end: n := 1 ; while true do f := A004154(n) : if isprime(f-1) then printf("%d, ", f-1) ; fi ; n := n+1 : od : # R. J. Mathar, Feb 27 2007
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PROG
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(PARI) v=[]; for(n=1, 500, if(ispseudoprime(t=n!/10^valuation(n!, 5)-1), v=concat(v, t))); v \\ Charles R Greathouse IV, Feb 14 2011
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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