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A250199 Smallest pseudoprime (>prime(n)) to base prime(n). 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A007535, see formula.

LINKS

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

FORMULA

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

EXAMPLE

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

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]

PROG

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

CROSSREFS

Cf. A007535, A090086, A108162, A098650.

Sequence in context: A057598 A271801 A322120 * A271874 A025335 A025327

Adjacent sequences:  A250196 A250197 A250198 * A250200 A250201 A250202

KEYWORD

nonn

AUTHOR

Eric Chen, Feb 21 2015

STATUS

approved

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Last modified January 17 10:57 EST 2021. Contains 340221 sequences. (Running on oeis4.)