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A102634
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Numbers k such that 2^k + 13 is prime.
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20
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2, 4, 8, 20, 38, 64, 80, 292, 1132, 4108, 19934, 125278, 175628, 282184
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OFFSET
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1,1
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COMMENTS
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For k in this sequence, the number 2^(k-1)*(2^k+13) has deficiency 14, cf. A141550. - M. F. Hasler, Jul 18 2016
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LINKS
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FORMULA
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EXAMPLE
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2^2+13 = 17 is prime.
2^4+13 = 29 is prime.
2^3+13 = 21 is not prime.
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MATHEMATICA
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Do[m = n; If[PrimeQ[2^n + 13], Print[n]], {n, 2, 19125, 2}] (* Robert G. Wilson v, Jan 24 2005 *)
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PROG
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(PARI) first(m)=my(v=vector(m), r=1); for(i=1, m, while(!isprime(2^r + 13), r++); v[i]=r; r++); v; \\ Anders Hellström, Aug 15 2015
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CROSSREFS
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Cf. A019434 (2^k+1), A057732 (2^k+3), A059242 (2^k+5), A057195 (2^k+7), A057196 (2^k+9), A102633 (2^k+11), A102634 (this), A057197 (2^k+15), A057200 (2^k+17), A057221 (2^k+19), A057201 (2^k+21), A057203 (2^k+23).
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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