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A102648
a(n) is the number of primes p between 0 and 99 such that 100*n+p is also prime.
0
9, 6, 15, 6, 5, 13, 5, 6, 12, 5, 6, 11, 6, 8, 11, 6, 7, 10, 6, 7, 10, 8, 6, 9, 4, 6, 11, 7, 4, 10, 3, 6, 13, 4, 8, 11, 5, 5, 11, 6, 4, 15, 3, 4, 10, 5, 6, 6, 7, 4, 10, 6, 3, 11, 5, 7, 7, 7, 3, 11, 5, 6, 14, 1, 4, 9, 5, 6, 10, 4, 3, 11, 2, 4, 12, 4, 7, 9, 3, 5, 8, 6, 5, 8, 5, 5, 11, 7, 4, 8, 4, 3
OFFSET
1,1
COMMENTS
a(n) <= 20
EXAMPLE
a(2)=6 because 11,211,23,223,29,229,41,241,71,271,83,283 are primes.
MATHEMATICA
With[{prs=Prime[Range[25]]}, Table[Length[Select[prs, PrimeQ[100n+#]&]], {n, 100}]] (* Harvey P. Dale, Sep 03 2022 *)
PROG
(PARI) a(n) = {nb = 0; forprime(p = 1, 99, nb += isprime(100*n + p); ); nb; } \\ Michel Marcus, Sep 04 2013
CROSSREFS
Sequence in context: A182873 A180856 A166520 * A272960 A040074 A088999
KEYWORD
nonn,easy
AUTHOR
Bill McEachen, Feb 03 2005
EXTENSIONS
Edited by Don Reble, Mar 28 2006
STATUS
approved