A163760 Exactly four distinct primes occur as substrings of the digits of n.

113, 131, 179, 197, 223, 231, 233, 235, 239, 253, 257, 271, 273, 283, 293, 297, 311, 313, 337, 347, 353, 359, 367, 371, 372, 375, 397, 431, 437, 473, 479, 531, 532, 547, 571, 573, 593, 597, 613, 617, 653, 713, 719, 723, 731, 732, 733, 735, 737, 739, 743

Offset

1,1

Comments

n, 10*n, 10*n+4, 10*n+6 and 10*n+8 are all in the sequence if any one of them is. - Robert Israel, Mar 21 2019

Links

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

Example

a(1) = 113 because "3" and "11" and "13" and "113" are prime substrings of "113".

Maple

filter:= proc(n) local L, m, SS, S, count, i, j;
  L:= convert(n, base, 10);
  m:= nops(L);
  SS:= remove(t -> t[-1]=0, {seq(seq(L[i..j], j=i..m), i=1..m)});
  nops(select(isprime, map(S -> add(S[i]*10^(i-1), i=1..nops(S)), SS))) = 4
end proc:
select(filter, [$100..1000]); # Robert Israel, Mar 21 2019

Crossrefs

Cf. A163754, A163759.

Sequence in context: A355856 A180441 A180407 * A179911 A344627 A187867

Adjacent sequences: A163757 A163758 A163759 * A163761 A163762 A163763

Keyword

base,easy,nonn

Author

Gil Broussard, Aug 03 2009

Status

approved