A117752 Number of prime 3-digit palindromes in base n.

2, 2, 3, 5, 6, 6, 13, 13, 15, 21, 20, 26, 25, 30, 36, 30, 37, 44, 50, 42, 59, 60, 61, 71, 75, 68, 89, 93, 109, 100, 111, 113, 118, 120, 133, 134, 142, 155, 162, 154, 166, 168, 187, 194, 220, 195, 207, 212, 235, 210, 243, 263, 247, 257, 293, 286, 296, 320, 304, 328

Offset

2,1

Comments

Is there a proof that a(n) > 0?

Links

Robert Israel, Table of n, a(n) for n = 2..1000

Maple

f:= proc(n) nops(select(isprime, [seq(seq(i*(n^2+1)+j*n, j=0..n-1), i=1..n-1)])) end proc:
map(f, [$2..100]); # Robert Israel, May 04 2020

Prog

(PARI) a(n)=local(t, i, j); t=0; for(i=1, n-1, for(j=0, n-1, if(isprime(i*(n^2+1)+j*n), t++))); t

Crossrefs

Cf. A060873.

Sequence in context: A098180 A357411 A270875 * A299775 A227191 A214045

Adjacent sequences: A117749 A117750 A117751 * A117753 A117754 A117755

Keyword

base,nonn

Author

Franklin T. Adams-Watters, Apr 14 2006

Status

approved