A230047 Palindromic primes with nondecreasing product of digits.

2, 3, 5, 7, 181, 191, 313, 353, 373, 383, 727, 757, 787, 797, 17971, 19891, 19991, 34843, 35753, 36563, 37573, 38783, 74747, 75557, 76667, 77977, 78787, 78887, 79997, 1987891, 1988891, 1998991, 3479743, 3487843, 3569653, 3586853, 3589853, 3689863, 3698963

Offset: 1

Author

Shyam Sunder Gupta, Oct 06 2013

Keywords

• nonn
• base

Comments

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

Links

• Shyam Sunder Gupta, Table of n, a(n) for n = 1..149

Crossrefs

Cf. A002385, A069802.

Programs

Mathematica

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