A121923 a(n) = smallest odd m such that (m^n + (m+2)^n)/2 is prime.

2, 17, 37, 4481, 101, 21601, 197, 257, 106921, 401, 237161, 577, 677, 391337974721, 815401, 1054721, 1297, 2093801, 1601, 3122281, 3759713, 6265001, 2917, 3137, 12981601, 16801793, 4357, 5477, 33396833, 2867651480694307162235699968001

Offset

1,1

Links

Table of n, a(n) for n=1..30.

Prog

(PARI) anplusbn(n) = { a=-1; forstep(a=1, n, 2, for(x=1, n, y=(a^x+(a+2)^x)/2; if(ispseudoprime(y), print1(y", "); break; ) ) ) }

Crossrefs

Sequence in context: A294560 A258977 A069042 * A212276 A000956 A031906

Adjacent sequences: A121920 A121921 A121922 * A121924 A121925 A121926

Keyword

nonn

Author

Cino Hilliard, Sep 10 2006, corrected Nov 15 2006

Status

approved