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 A113239 #11 Jul 07 2024 13:16:28
%S A113239 2,3,5,11,17,23,31,37,43,79,193,491,503,653,883,1201,10607,19009,
%T A113239 19469,19489,34963,35809,46499,223273,223313,391231,409817,410731,
%U A113239 532159,634061,754549,1383769,1389533,2552621,2555753,3311233,4477453,4700621
%N A113239 Prime differences of tribonacci numbers.
%C A113239 A113238 is the difference set of tribonacci numbers. A113188-A113194 deal with difference sets of Fibonacci numbers and Lucas numbers and primes in those difference sets.
%F A113239 Intersection of primes A000040 and difference set of tribonacci numbers A113238. Positive prime values of {A000073(i) - A000073(j) such that i>j}.
%e A113239 a(1) = 2 because 4 - 2 = 2 where 4 and 2 are tribonacci numbers.
%e A113239 a(2) = 3 because 7 - 4 = 3 where 7 and 4 are tribonacci numbers.
%e A113239 a(3) = 5 because 7 - 2 = 5 where 7 and 2 are tribonacci numbers.
%e A113239 a(4) = 11 because 13 - 2 = 11 where 13 and 2 are tribonacci numbers.
%e A113239 a(5) = 17 because 24 - 7 = 17 where 24 and 7 are tribonacci numbers.
%t A113239 Select[Union[Flatten[Differences/@Subsets[Drop[LinearRecurrence[{1, 1, 1}, {0, 0, 1}, 29],2],{2}]]],PrimeQ] (* _James C. McMahon_, Jun 23 2024 *)
%Y A113239 Cf. A000040, A000073, A113188-A113194, A113238.
%K A113239 easy,nonn
%O A113239 1,1
%A A113239 _Jonathan Vos Post_, Oct 19 2005