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A248165 a(1)=252; for n>=1, a(n+1) is the smallest palindromic 5-almost prime with a(n) as a central substring.

%I A248165 #29 Dec 02 2014 20:59:14
%S A248165 252,92529,189252981,1218925298121,212189252981212,12121892529812121,
%T A248165 8121218925298121218,781212189252981212187,1678121218925298121218761,
%U A248165 216781212189252981212187612,22167812121892529812121876122,2221678121218925298121218761222
%N A248165 a(1)=252; for n>=1, a(n+1) is the smallest palindromic 5-almost prime with a(n) as a central substring.
%C A248165 The 5-almost primes are the numbers that are the product of exactly five (not necessarily distinct).
%e A248165 a(1) = 252 = 2*2*3*3*7;
%e A248165 a(2) = 92529 = 3*3*3*23*149.
%t A248165 d[n_]:= IntegerDigits[n]; t = {x = 252}; Do[i = 1; While[!PrimeOmega[y = FromDigits[Flatten[{z = d[i], d[x], Reverse[z]}]]]==5, i++]; AppendTo[t, x = y], {n, 13}]; t
%Y A248165 Cf. A014614, A247483, A247484, A248047.
%K A248165 nonn,base
%O A248165 1,1
%A A248165 _Michel Lagneau_, Dec 01 2014