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A230042 Palindromic primes with strictly increasing product of digits. 1
2, 3, 5, 7, 181, 191, 353, 373, 383, 727, 757, 787, 797, 19891, 19991, 34843, 35753, 36563, 37573, 38783, 74747, 75557, 76667, 77977, 78787, 78887, 79997, 1987891, 1988891, 1998991, 3479743, 3487843, 3569653, 3586853, 3589853, 3689863, 3698963, 3799973 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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 and Chai Wah Wu, Table of n, a(n) for n = 1..200 (terms for n = 1..128 from Shyam Sunder Gupta)

EXAMPLE

a(6) = 191, product of digits is 9; a(7) = 353, product of digits is 45 and 45 > 9.

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

nxt[{p_, d_}]:=Module[{n=NextPrime[p]}, While[!PalindromeQ[n]||Times@@ IntegerDigits[ n]<=d, n=NextPrime[n]]; {n, Times@@IntegerDigits[n]}]; NestList[nxt, {2, 2}, 40][[All, 1]] (* Harvey P. Dale, Sep 30 2018 *)

CROSSREFS

Cf. A002385, A230041, A007954, A053666.

Sequence in context: A098463 A064155 A230047 * A230045 A069803 A083184

Adjacent sequences:  A230039 A230040 A230041 * A230043 A230044 A230045

KEYWORD

nonn,base

AUTHOR

Shyam Sunder Gupta, Oct 06 2013

STATUS

approved

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Last modified May 7 10:18 EDT 2021. Contains 343650 sequences. (Running on oeis4.)