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

1,1

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

Links

Table of n, a(n) for n=1..18.

Example

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

Prog

(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

Crossrefs

Cf. A088603, A127891.

Sequence in context: A208316 A096497 A247153 * A127891 A110369 A212071

Adjacent sequences: A088601 A088602 A088603 * A088605 A088606 A088607

Keyword

base,nonn

Author

Amarnath Murthy, Oct 15 2003

Extensions

More terms from David Wasserman, Aug 12 2005

Status

approved