This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A134071 #14 Feb 16 2025 08:33:06
%S A134071 31,431,117431,19912376472918117431
%N A134071 Primes in A134072.
%C A134071 A134072 = {1, 31, 431, 7431, 117431, 18117431, 2918117431, 472918117431, 76472918117431, 12376472918117431, 19912376472918117431, ...} = concatenation of Lucas numbers in reverse order. Indices of prime terms in A134072 are {2, 3, 5, 11, ...}.
%C A134071 No further terms through 500 Lucas numbers. - _Harvey P. Dale_, Aug 17 2013
%H A134071 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LucasNumber.html">Lucas Number</a>
%H A134071 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SmarandacheSequences.html">Smarandache Sequences</a>
%e A134071 a(1) = A134072(2) = 31.
%e A134071 a(2) = A134072(3) = 431.
%e A134071 a(3) = A134072(5) = 117431.
%t A134071 nn=500;With[{lucs=LucasL[Range[nn]]},Select[Table[FromDigits[ Flatten[ IntegerDigits/@ Reverse[ Take[lucs,n]]]],{n,nn}],PrimeQ]] (* _Harvey P. Dale_, Aug 17 2013 *)
%Y A134071 Cf. A000204 (Lucas numbers).
%Y A134071 Cf. A130774 (concatenation of Lucas numbers).
%Y A134071 Cf. A019523 (concatenation of Fibonacci numbers).
%Y A134071 Cf. A038399 (concatenation of first n nonzero Fibonacci numbers in reverse order).
%Y A134071 Cf. A134072 (concatenation of A000204 Lucas numbers (beginning at 1) in reverse order).
%Y A134071 Cf. A134069 (primes in A038399).
%Y A134071 Cf. A134070 (primes in A130774).
%K A134071 hard,more,nonn,base
%O A134071 1,1
%A A134071 _Alexander Adamchuk_, Oct 06 2007
%E A134071 Edited by _Charles R Greathouse IV_, Apr 24 2010