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A103959 Minimum prime p such that prime(n)*p - 2 is prime. 2
2, 3, 3, 3, 3, 3, 5, 7, 3, 11, 13, 3, 11, 3, 3, 3, 5, 3, 3, 3, 7, 19, 11, 5, 7, 5, 3, 23, 7, 3, 3, 5, 3, 7, 5, 31, 7, 3, 3, 5, 17, 3, 3, 3, 5, 19, 3, 7, 29, 7, 5, 5, 61, 3, 3, 3, 11, 3, 3, 11, 7, 3, 3, 5, 3, 5, 3, 3, 3, 7, 11, 11, 19, 3, 61, 5, 29, 7, 3, 7, 17 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Conjecture: a(n) <= prime(n). Tested to n=10000.

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

EXAMPLE

Prime(1)*2-2=2 is prime, so a(1)=2;

Prime(2)*3-2=7 is prime, so a(2)=3;

MATHEMATICA

Table[p=Prime[n]; k=1; pk=Prime[k]; cp=p*pk-2; While[ !PrimeQ[cp], k=k+1; pk=Prime[k]; cp=p*pk-2]; pk, {n, 100}]

CROSSREFS

Sequence in context: A055767 A029110 A249420 * A035375 A093493 A087162

Adjacent sequences:  A103956 A103957 A103958 * A103960 A103961 A103962

KEYWORD

easy,nonn

AUTHOR

Lei Zhou, Feb 22 2005

STATUS

approved

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Last modified April 25 16:59 EDT 2019. Contains 322461 sequences. (Running on oeis4.)