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A088427 Number of primes in arithmetic progression starting with 23 and with d=2n. 9
1, 1, 2, 2, 1, 1, 2, 1, 3, 2, 1, 3, 1, 1, 4, 1, 1, 2, 2, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 4, 2, 1, 3, 2, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 4, 1, 1, 3, 2, 1, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 2, 1, 3, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 1, 3, 2, 1, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Arithmetic progression is stopped when next term is not prime. E.g. for n=15 (d=30), a=3, that is 23,53,83,113 are prime, while next term, 143, is not prime.

LINKS

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

MATHEMATICA

bb={}; Do[s=1; Do[If[PrimeQ[23+k*d], s=s+1, bb={bb, s}; Break[]], {k, 10}], {d, 2, 200, 2}]; Flatten[bb]

CROSSREFS

Cf. A088420, A088421, A088422, A088423, A088424, A088425, A088426, A088428, A088429.

Sequence in context: A226621 A112933 A270650 * A255350 A104482 A333632

Adjacent sequences:  A088424 A088425 A088426 * A088428 A088429 A088430

KEYWORD

easy,nonn

AUTHOR

Zak Seidov, Sep 29 2003

STATUS

approved

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Last modified April 15 20:40 EDT 2021. Contains 342977 sequences. (Running on oeis4.)