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A230045 Palindromic primes with strictly increasing sum of digits. 1

%I

%S 2,3,5,7,181,191,373,383,727,757,787,797,17971,19891,19991,76667,

%T 77977,78887,79997,1987891,1988891,1998991,3799973,3899983,3998993,

%U 7897987,7996997,9888889,9889889,9989899,199999991,768989867,779969977,779999977,798989897

%N Palindromic primes with strictly increasing sum of digits.

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

%H Shyam Sunder Gupta, <a href="/A230045/b230045.txt">Table of n, a(n) for n = 1..63</a>

%e a(6) = 191, sum of digits is 11; a(7) = 373, sum of digits is 13 and 13 > 11.

%t a = {}; t = 0; Do[z = n*10^(IntegerLength[n] - 1) + FromDigits@Rest@Reverse@IntegerDigits[n]; If[PrimeQ[z], s = Apply[Plus, IntegerDigits[z]]; If[s > t, t = s; AppendTo[a, z]]], {n, 10^5}]; a

%Y Cf. A002385, A061248.

%K nonn,base

%O 1,1

%A _Shyam Sunder Gupta_, Oct 06 2013

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Last modified May 20 16:35 EDT 2022. Contains 353875 sequences. (Running on oeis4.)