A102648 a(n) is the number of primes p between 0 and 99 such that 100*n+p is also prime.

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

Links

Table of n, a(n) for n=1..92.

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

Adjacent sequences: A102645 A102646 A102647 * A102649 A102650 A102651

Keyword

nonn,easy

Author

Bill McEachen, Feb 03 2005

Extensions

Edited by Don Reble, Mar 28 2006

Status

approved