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 A097785 #5 Mar 31 2012 20:30:55
%S A097785 497,1771,2279,3161,3487,5149,5357,5993,6439,8129,9451,9731,11477,
%T A097785 15049,16469,18337,19901,25879,26333,28681,29159,34717,40187,43069,
%U A097785 48517,50401,54947,60379,61073,62479,67529,69749,72011,73537,79001,88829
%N A097785 Counterexamples to the conjecture that an even, prime-indexed triangular plus 1 equals a prime or that an odd, prime-indexed triangular minus 2 equals a prime.
%C A097785 In the entry for 496, Wells remarks that it is the smallest counterexample to the conjecture that an even, prime-indexed triangular plus 1 equals a prime, since 497 is not prime.
%D A097785 David Wells, The Penguin Dictionary of Curious and Interesting Numbers.
%t A097785 tri[n_] := n(n + 1)/2; tp = Table[ tri[ Prime[n]], {n, 2, 85}]; f[n_] := If[ OddQ[n], n - 2, n + 1]; Select[f /@ tp, Not[ PrimeQ[ # ]] &]
%Y A097785 Cf. A096333.
%K A097785 nonn
%O A097785 1,1
%A A097785 _Alonso del Arte_ and _Robert G. Wilson v_, Aug 24 2004