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A231426 Least prime such that at most n digits may be appended to the right, preserving primality at each step. 1
53, 11, 97, 17, 71, 43, 13, 2, 19, 103, 409, 1457011 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..11.

FORMULA

a(n) is the least prime p=prime(k) such that A232128(p) (= A232127(k)) = n.

If a(n) = p, then a(n) = floor(A232129(p)/10^A232128(p)).

EXAMPLE

a(7) = 2 is the least prime which starts several sequences of 1+7 primes, e.g., (2, 23, 239, 2393, ..., 23399339) and others leading at most to 29399999 = A232129(2), where a digit is appended 7 times to yield a prime after each step, while it is not possible in any of the "branches" to append one more digit to the last term, preserving primality.

CROSSREFS

Cf. A232128, A232127, A232126, A232125.

Sequence in context: A143294 A143428 A143385 * A048602 A048606 A033373

Adjacent sequences:  A231423 A231424 A231425 * A231427 A231428 A231429

KEYWORD

nonn,base,more

AUTHOR

Michel Marcus and M. F. Hasler, Nov 19 2013

STATUS

approved

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Last modified July 25 10:40 EDT 2017. Contains 289792 sequences.