Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #27 Feb 07 2021 14:57:28
%S 2,7,17,191,1051,1934063
%N Smaller of two successive primes with a palindromic product.
%C No further terms less than 1.38 * 10^10. - _Michael S. Branicky_, Feb 07 2021
%H Patrick De Geest, <a href="http://www.worldofnumbers.com/sequenc.htm">More palindromic products of integer sequences</a>
%e 17 is in the sequence because 17 * 19 = 323.
%e 19 is not in the sequence because 19 * 23 = 437.
%t p = 2; t = {}; Do[q = NextPrime[p]; If[Reverse[x = IntegerDigits[p * q]] == x, AppendTo[t, p]]; p = q, {n, 150000}]; t (* _Jayanta Basu_, Jun 05 2013 *)
%t Prime[#]&/@Flatten[Position[Times@@@Partition[Prime[Range[1934100]], 2, 1], _?(PalindromeQ[#] &)]] (* _Harvey P. Dale_, May 14 2019 *)
%o (Python)
%o from sympy import nextprime
%o def ispal(n): s = str(n); return s == s[::-1]
%o p, q = 2, 3
%o while True:
%o if ispal(p*q): print(p)
%o p, q = q, nextprime(q) # _Michael S. Branicky_, Feb 07 2021
%Y Cf. A028978, A028979.
%K nonn,base,more
%O 1,1
%A _Patrick De Geest_
%E Edited by _N. J. A. Sloane_, May 04 2007