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A064632 Smallest prime p such that n = (p-1)/(q-1) for some prime q. 7
3, 7, 5, 11, 7, 29, 17, 19, 11, 23, 13, 53, 29, 31, 17, 103, 19, 191, 41, 43, 23, 47, 97, 101, 53, 109, 29, 59, 31, 311, 193, 67, 137, 71, 37, 149, 229, 79, 41, 83, 43, 173, 89, 181, 47, 283, 97, 197, 101, 103, 53, 107, 109, 331, 113, 229, 59, 709, 61, 367, 373 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Daria Micovic, Table of n, a(n) for n = 2..10000

Matthew M. Conroy, A sequence related to a conjecture of Schinzel, , J. Integ. Seqs. Vol. 4 (2001), #01.1.7.

EXAMPLE

a(7) = 29 because (29-1)/(5-1).

MATHEMATICA

NextPrim[n_] := (k = n + 1; While[ !PrimeQ[k], k++ ]; k); Do[p = 2; While[q = (p - 1)/n + 1; !PrimeQ[q] || q >= p, p = NextPrim[p]]; Print[p], {n, 2, 100} ]

spp[n_]:=Module[{p=2}, While[!PrimeQ[(p-1)/n+1], p=NextPrime[p]]; p]; Array[ spp, 70, 2] (* Harvey P. Dale, Aug 22 2019 *)

PROG

(Sage)

def A064632(n):

    p, q = 0, 0

    while not (q.is_prime() and q < p):

        p = next_prime(p)

        if p % n != 1: continue

        q = (p - 1) // n + 1

    return p # Daria Micovic, Apr 13 2016

(PARI) a(n) = {forprime(p=2, , forprime(q=2, p-1, if ((p-1)/(q-1) == n, return (p)); ); ); } \\ Michel Marcus, Apr 16 2016

CROSSREFS

Similar to but not the same as A034694. Cf. A064652 (q-values), A064673.

Sequence in context: A254929 A066677 A061026 * A216487 A328984 A328190

Adjacent sequences:  A064629 A064630 A064631 * A064633 A064634 A064635

KEYWORD

easy,nonn

AUTHOR

Robert G. Wilson v, Oct 16 2001

EXTENSIONS

Definition corrected by Stephanie Anderson, Apr 16 2016

STATUS

approved

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Last modified June 5 23:10 EDT 2020. Contains 334858 sequences. (Running on oeis4.)