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A038711
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a(n) is the smallest m such that A002110(n) + m is prime.
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9
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1, 1, 1, 1, 1, 1, 17, 19, 23, 37, 61, 1, 61, 71, 47, 107, 59, 61, 109, 89, 103, 79, 151, 197, 101, 103, 233, 223, 127, 223, 191, 163, 229, 643, 239, 157, 167, 439, 239, 199, 191, 199, 383, 233, 751, 313, 773, 607, 313, 383, 293, 443, 331, 283, 277, 271, 401, 307
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OFFSET
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0,7
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COMMENTS
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LINKS
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FORMULA
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a(n) = Min(1, A005235(n)); a(n)=1 for n=1, 2, 3, 4, 5, 11, 75, ...
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EXAMPLE
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For n=11, 1 + A002110(11) = 200560490131 < 200560490197 = 67 + A002110(11); therefore, a(11)=1 but A005235(11)=67.
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MAPLE
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p:= proc(n) option remember; `if`(n<1, 1, p(n-1)*ithprime(n)) end:
a:= n-> nextprime(p(n))-p(n):
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MATHEMATICA
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nmax=2^16384; npd=1; n=1; npd=npd*Prime[n]; While[npd<nmax, tt=1; cp=npd+tt; While[ !(PrimeQ[cp]), tt=tt+2; cp=cp+2]; Print[tt]; n=n+1; npd=npd*Prime[n]] (* Lei Zhou, Feb 15 2005 *)
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PROG
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(PARI) a(n) = my(P=vecprod(primes(n))); nextprime(P+1) - P; \\ Michel Marcus, Dec 12 2023
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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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