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A088420
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Number of primes in arithmetic progression starting with 3 and with d=2n.
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10
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3, 3, 1, 3, 3, 1, 3, 2, 1, 3, 1, 1, 2, 3, 1, 1, 3, 1, 3, 3, 1, 2, 1, 1, 3, 1, 1, 2, 2, 1, 1, 3, 1, 3, 2, 1, 1, 2, 1, 3, 1, 1, 2, 1, 1, 1, 3, 1, 3, 2, 1, 3, 2, 1, 3, 1, 1, 1, 1, 1, 1, 3, 1, 2, 1, 1, 3, 2, 1, 1, 1, 1, 2, 2, 1, 1, 3, 1, 1, 2, 1, 3, 1, 1, 2, 1, 1, 2, 3, 1, 1, 1, 1, 3, 3, 1, 2, 2, 1, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Arithmetic progression is stopped when next term is not prime. E.g. for n=5, a=3, that is 3,13,23 are prime, while next term, 33, is not prime.
a(n) <= 3 because 3+3*d is divisible by 3. [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), May 14 2009]
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PROG
| (MAGMA) npap3:=function(d) c:=1; p:=3+d; while IsPrime(p) do c+:=1; p+:=d; end while; return c; end function; [ npap3(2*n): n in [1..105] ]; [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), May 14 2009]
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CROSSREFS
| Cf. A088421, A088422, A088423, A088424, A088425, A088426, A088427, A088428, A088429.
Cf. A115334. [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), May 14 2009]
Sequence in context: A039992 A101988 A200606 * A103585 A154595 A144437
Adjacent sequences: A088417 A088418 A088419 * A088421 A088422 A088423
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KEYWORD
| easy,nonn
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AUTHOR
| Zak Seidov (zakseidov(AT)yahoo.com), Sep 29 2003
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