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A088604 a(n) = smallest prime in which n substrings containing the least significant digit are primes. 2
2, 13, 113, 1223, 12113, 121283, 1237547, 12184967, 124536947, 1219861613, 12181833347, 121339693967, 1213536676883, 12673876537547, 121848768729173, 1275463876537547, 12429121339693967, 165678739293946997 (list; graph; refs; listen; history; text; internal format)
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++)); (Wasserman)

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

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Last modified February 27 04:21 EST 2021. Contains 341646 sequences. (Running on oeis4.)