A226533 a(n) = smallest integer m such that m^n is a sum of two successive primes.

5, 6, 2, 150, 22, 82, 2, 258, 70, 30, 42, 18, 2, 12, 262, 58, 460, 36, 552, 24, 318, 344, 450, 54, 274, 88, 36, 92, 90, 188, 554, 20, 404, 700, 240, 6, 136, 262, 578, 222, 2182, 276, 162, 60, 142, 326, 176, 198, 930, 1116

Offset

1,1

Links

Zak Seidov, Table of n, a(n) for n = 1..150

Example

5^1 = 5 = 2 + 3, 6^2 = 36  = 17 + 19, 2^3 = 8 = 3 + 5, 150^4 =506250000 = 253124999 + 253125001.

Mathematica

a[n_] := For[m = 2, True, m++, p = m^n/2 // NextPrime[#, -1]&; q = NextPrime[p]; If[p + q == m^n, Print["a(", n, ") = ", m]; Return[m]]]; Table[a[n], {n, 1, 50}] (* Jean-François Alcover, Jun 10 2013 *)
tsp[n_]:=Module[{m=1, t}, t=m^n; While[NextPrime[t/2]+NextPrime[t/2, -1]! = t, m++; t=m^n]; m]; Array[tsp, 50] (* Harvey P. Dale, Nov 10 2014 *)

Prog

(PARI) a(n)=if(n==1, return(5)); my(m=1, M, p); while(1, M=m++^n; p=precprime(M/2); ispseudoprime(M-p) && M-p==nextprime(M/2) && return(m)) \\ Charles R Greathouse IV, Jun 10 2013

Crossrefs

a(2) = 6 = A074924(1), a(3) = 2 = A074925(1). Cf. A001043, A001597.

Sequence in context: A072733 A018851 A260463 * A011499 A242813 A106599

Adjacent sequences: A226530 A226531 A226532 * A226534 A226535 A226536

Keyword

nonn

Author

Zak Seidov, Jun 09 2013

Extensions

a(41)-a(50) from Jean-François Alcover, Jun 10 2013

Status

approved