|
|
A226533
|
|
a(n) = smallest integer m such that m^n is a sum of two successive primes.
|
|
1
|
|
|
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
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
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
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|