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A088424 Number of primes in arithmetic progression starting with 13 and with d=2n. 9
1, 2, 2, 1, 2, 1, 1, 2, 2, 1, 1, 3, 1, 2, 4, 1, 2, 1, 1, 2, 1, 1, 2, 4, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 1, 3, 1, 2, 6, 1, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 3, 1, 2, 1, 1, 2, 2, 1, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 5, 1, 2, 1, 1, 2, 1, 1, 2, 3, 1, 1, 1, 1, 2, 3, 1, 2, 2, 1, 1, 1, 1, 1, 4, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Arithmetic progression is stopped when next term is not prime. E.g. for n=15, a=4, that is 13,43,73,103 are prime, while next term, 133, is not prime.

LINKS

Table of n, a(n) for n=1..100.

MATHEMATICA

bb={}; Do[s=1; Do[If[PrimeQ[13+k*d], s=s+1, bb={bb, s}; Break[]], {k, 10}], {d, 2, 200, 2}]; Flatten[bb]

CROSSREFS

Cf. A088420, A088421, A088422, A088423, A088425, A088426, A088427, A088428, A088429.

Sequence in context: A246144 A192763 A001285 * A317960 A270642 A270643

Adjacent sequences:  A088421 A088422 A088423 * A088425 A088426 A088427

KEYWORD

easy,nonn

AUTHOR

Zak Seidov, Sep 29 2003

STATUS

approved

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Last modified May 18 00:43 EDT 2021. Contains 343992 sequences. (Running on oeis4.)