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A103630 Numbers n such that the string 235n is the decimal expansion of a prime number. 2
1, 7, 31, 37, 39, 49, 57, 61, 63, 67, 81, 93, 99, 111, 117, 159, 171, 177, 181, 199, 211, 231, 241, 243, 273, 289, 307, 309, 337, 349, 369, 397, 439, 441, 447, 483, 489, 493, 513, 519, 523, 537, 541, 553, 559, 577, 591, 601, 607, 621, 661, 663, 673, 679, 699 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

1 is in the sequence because 2351 is prime.

49 is in the sequence because 23549 is prime.

171 is in the sequence because 235171 is prime.

MAPLE

map(p->p[2], select(p -> isprime(235*10^p[1]+p[2]), [seq([1, k], k=1..9, 2), seq(seq([d, k], k=10^(d-1)+1..10^d, 2), d=2..3)])); # Robert Israel, Jan 11 2018

PROG

(MAGMA) [ n: n in [1..800] | IsPrime(Seqint(Intseq(n) cat [5, 3, 2])) ]; // Klaus Brockhaus, Feb 02 2011

CROSSREFS

Sequence in context: A122654 A184121 A167768 * A205711 A040064 A241101

Adjacent sequences:  A103627 A103628 A103629 * A103631 A103632 A103633

KEYWORD

base,nonn

AUTHOR

Parthasarathy Nambi, Mar 25 2005

STATUS

approved

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Last modified February 26 13:41 EST 2021. Contains 341632 sequences. (Running on oeis4.)