cp's OEIS Frontend

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.

%I A233692 #39 Jan 01 2022 08:11:34
%S A233692 2,23,23,239,239,239,3413,14249,524219,4167379,324550981,2589767209,
%T A233692 346333812907
%N 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.
%C A233692 This sequence was produced as solution to the problem 1270 of _Claudio Meller_'s website (see link).
%H A233692 Claudio Meller, <a href="http://simplementenumeros.blogspot.mx/2013/12/1270-usando-el-producto-digital-ii.html">1270 - Usando el producto digital II</a>, Números y algos mas (in Spanish).
%e A233692 For n=3, initial prime=23, set {23, 29, 47} because 23 -> 23+2*3=29 -> 29+2*9=47.
%e A233692 For n=2 to 9, the sets are
%e A233692       23,     29;
%e A233692       23,     29,     47;
%e A233692      239,    293,    347,    431;
%e A233692      239,    293,    347,    431,    443;
%e A233692      239,    293,    347,    431,    443,    491;
%e A233692     3413,   3449,   3881,   4073,   4157,   4297,   4801;
%e A233692    14249,  14537,  14957,  16217,  16301,  16319,  16481,  16673;
%e A233692   524219, 524939, 534659, 550859, 559859, 640859, 649499, 719483, 725531.
%o A233692 (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
%Y A233692 Cf. A051801, A063114, A233783.
%K A233692 nonn,base,hard,more
%O A233692 1,1
%A A233692 _Carlos Rivera_, Dec 14 2013
%E A233692 a(13) from _Giovanni Resta_, Dec 15 2013