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 A294369 #34 Feb 03 2018 13:12:46 %S A294369 0,1,2,4,8,10 %N A294369 Indices of Fibonacci numbers (A000045) that are triangular numbers (A000217). %C A294369 The sequence of Fibonacci numbers that are also triangular numbers begins: 0, 1, 1, 3, 21, 55. That is, 0 and 1 followed by A039595. %e A294369 Fibonacci(10)=55 is a triangular number, therefore 10 is in the sequence. %Y A294369 Cf. A000045, A000217, A039595, A162394, A121343, A121874. %K A294369 nonn,fini,full %O A294369 1,3 %A A294369 _Alex Ratushnyak_, Jan 24 2018