A250199 Smallest pseudoprime (>prime(n)) to base prime(n).

341, 91, 124, 25, 15, 21, 45, 45, 33, 35, 49, 45, 105, 77, 65, 65, 87, 91, 85, 105, 111, 91, 105, 99, 105, 175, 133, 133, 117, 133, 153, 143, 148, 161, 175, 175, 186, 186, 231, 205, 185, 195, 217, 276, 231, 225, 217, 231, 285, 285, 259, 255, 363, 289, 301, 341, 286, 341, 322, 329

Offset: 1

Author

Eric Chen, Feb 21 2015

Keywords

• nonn

Comments

Subsequence of A007535, see formula.

Examples

			a(7) = 45 because the 7th prime is 17, and the smallest pseudoprime (> 17) to base 17 is 45.
		

Links

• Eric Chen, Table of n, a(n) for n = 1..4096

Crossrefs

Cf. A007535, A090086, A108162, A098650.

Programs

Mathematica

f[n_] := Block[{b = Prime[n], k = Prime[n] + 1}, While[PrimeQ[k] || PowerMod[b, k - 1, k] != 1, k++]; k]; Array[f, 60]

PARI

a(n) = for(k=prime(n)+1,2^24,if(Mod(prime(n),k)^(k-1)==Mod(1,k) && !isprime(k),return(k)))

Formula

a(n) = A007535(A000040(n)).