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A233692 The smallest prime that produces a set of n primes such that every prime after the first one is equal to the previous plus the product of its nonzero digits. 2
2, 23, 23, 239, 239, 239, 3413, 14249, 524219, 4167379, 324550981, 2589767209, 346333812907 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This sequence was produced as solution to the problem 1270 of Claudio Meller's website (see link).

LINKS

Table of n, a(n) for n=1..13.

Claudio Meller, 1270 - Usando el producto digital II, NĂºmeros y algos mas (in Spanish).

EXAMPLE

For n=3, initial prime=23, set {23, 29, 47} because 23 -> 23+2*3=29 -> 29+2*9=47.

For n=2 to 9, the sets are:

23, 29;

23, 29, 47;

239, 293, 347, 431;

239, 293, 347, 431, 443;

239, 293, 347, 431, 443, 491;

3413, 3449, 3881, 4073, 4157, 4297, 4801;

14249, 14537, 14957, 16217, 16301, 16319, 16481, 16673;

524219, 524939, 534659, 550859, 559859, 640859, 649499, 719483, 725531;

PROG

(PARI) checkp(p, n) = {ok = isprime(p); for (i=1, n, print1(p, ", "); digs = digits(p); np = p + prod(i=1, #digs, if (d=digs[i], d, 1)); p = np; if (i != n, ok = ok && isprime(p)); ); ok; } \\ Michel Marcus, Dec 15 2013

CROSSREFS

Cf. A051801, A063114, A233783.

Sequence in context: A153654 A153656 A242037 * A084323 A131983 A153718

Adjacent sequences:  A233689 A233690 A233691 * A233693 A233694 A233695

KEYWORD

nonn,base,hard,more

AUTHOR

Carlos Rivera, Dec 14 2013

EXTENSIONS

a(13) from Giovanni Resta, Dec 15 2013

STATUS

approved

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Last modified July 22 14:33 EDT 2019. Contains 325222 sequences. (Running on oeis4.)