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Palindromic primes with nondecreasing product of digits.
1

%I #11 Dec 12 2015 16:48:37

%S 2,3,5,7,181,191,313,353,373,383,727,757,787,797,17971,19891,19991,

%T 34843,35753,36563,37573,38783,74747,75557,76667,77977,78787,78887,

%U 79997,1987891,1988891,1998991,3479743,3487843,3569653,3586853,3589853,3689863,3698963

%N Palindromic primes with nondecreasing product of digits.

%C a(1) = 2; a(n+1) is the smallest palindromic prime with product of digits >= product of digits of a(n).

%H Shyam Sunder Gupta, <a href="/A230047/b230047.txt">Table of n, a(n) for n = 1..149</a>

%t a = {}; t = 0; Do[z = n*10^(IntegerLength[n] - 1) + FromDigits@Rest@Reverse@IntegerDigits[n]; If[PrimeQ[z], s = Apply[Times, IntegerDigits[z]]; If[s >= t, t = s; AppendTo[a, z]]], {n, 10^4}]; a

%Y Cf. A002385, A069802.

%K nonn,base

%O 1,1

%A _Shyam Sunder Gupta_, Oct 06 2013

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Last modified September 24 11:47 EDT 2024. Contains 376196 sequences. (Running on oeis4.)