A088604 a(n) = smallest prime in which n substrings containing the least significant digit are primes.

2, 13, 113, 1223, 12113, 121283, 1237547, 12184967, 124536947, 1219861613, 12181833347, 121339693967, 1213536676883, 12673876537547, 121848768729173, 1275463876537547, 12429121339693967, 165678739293946997

Offset: 1

Author

Amarnath Murthy, Oct 15 2003

Keywords

• base
• nonn

Comments

a(n) need not contain a(n-1) as a substring.

We exclude substrings that begin with 0, so a(3) is not 103. - David Wasserman, Aug 12 2005

Agrees with A127891 for 24 terms, but A127891 ends there while this sequence continues. - Ray Chandler, Mar 13 2007

Examples

			a(4) = 1223 in which the four substrings containing the LSD (3,23,223,1223) are primes.
		

Crossrefs

Cf. A088603, A127891.

Programs

PARI

f(n, d, digs, spare) = local(p, r, found); if (!d, return(n)); found = 0; for (i = 0, 9, p = n + i*10^digs; if ((i && isprime(p)) || spare, r = f(p, d - 1, digs + 1, spare - 1 + (i && isprime(p)))); if (r && (r < found || !found), found = r)); found;
a(n) = local(i, r); i = 0; while (1, r = f(0, n + i, 0, i); if (r, return(r), i++)); \\ David Wasserman, Aug 12 2005

Extensions

More terms from David Wasserman, Aug 12 2005