

A096915


Smallest prime which when appended to n produces a prime.


8



3, 3, 7, 3, 3, 7, 3, 3, 7, 3, 3, 7, 7, 23, 7, 3, 3, 11, 3, 11, 11, 3, 3, 11, 7, 3, 7, 3, 3, 7, 3, 17, 7, 7, 3, 7, 3, 3, 7, 13, 11, 11, 3, 3, 7, 3, 23, 7, 19, 3, 13, 3, 23, 7, 7, 3, 7, 7, 3, 7, 3, 11, 11, 3, 3, 19, 3, 3, 11, 13, 29, 7, 3, 3, 7, 43, 3, 7, 7, 11, 11, 3, 11, 19, 3, 3, 7, 3, 23, 7, 37, 41
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OFFSET

1,1


LINKS

T. D. Noe, Table of n, a(n) for n=1..10000


EXAMPLE

a(20)=11 because 11 is prime and 2011 is the smallest prime starting with 20 (2003 is not allowed).


MATHEMATICA

f[n_] := Block[{p = 2, a = IntegerDigits[n]}, While[ !PrimeQ[ FromDigits[ Join[a, IntegerDigits[ Prime[p]]] ]], p++ ]; Prime[p]]; Table[ f[n], {n, 92}] (* Robert G. Wilson v, Aug 20 2004 *)


PROG

(PARI) A096915(n) = { local(p=1); until(isprime(eval(Str(n, p=nextprime(p+2)))), ); p} \\ M. F. Hasler, Jan 05 2009


CROSSREFS

Cf. A088606, A089777 (the resulting primes). Records: A137177, A144593.
Sequence in context: A256784 A089488 A076560 * A249806 A249382 A285387
Adjacent sequences: A096912 A096913 A096914 * A096916 A096917 A096918


KEYWORD

nonn,base


AUTHOR

Bodo Zinser, Aug 18 2004


EXTENSIONS

More terms from Robert G. Wilson v, Aug 20 2004
Crossreference to indices of records corrected by M. F. Hasler, Jan 14 2009


STATUS

approved



