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 A345715 #8 Jun 30 2021 16:06:41 %S A345715 5,10,20,5,9,4,7,5,13,1,23,25,5,13,5,4,7,4,2,119,800,5,4,4,7,4,2,119, %T A345715 36,5,1,23,24,25,5,4,4,7,5,4,7,5,9,4,7,5,13,26,2,179,5,9,23,1,23,25,5, %U A345715 13,26,2,179,1,2,1,5,13,5,4,7,5,9,4,7,5,13,26,2,179,5,4,7,4,2,119,36,5,1,23,24,25,5,4,4 %N A345715 Lexicographically earliest sequence of distinct positive terms such that the English names of the entries form a new sequence of English names where every original entry is doubled (repetitions allowed, see the Comments section). %C A345715 The first English names of the sequence are: %C A345715 FIVE, TEN, TWENTY, FIVE, NINE, FOUR, SEVEN, FIVE, THIRTEEN, ONE, TWENTY-THREE, TWENTY-FIVE, FIVE, THIRTEEN, FIVE, FOUR, SEVEN, FOUR, TWO, ONE HUNDRED NINETEEN, EIGHT HUNDRED, FIVE, FOUR, FOUR, ... %C A345715 If we now take the 5th letter of the above English sequence (T), the 10th (E) and the 20th (N) we spell T.E.N. and 10 is the double of a(1) = 5. We then take again the 5th letter of the sequence (T), the 9th (W), the 4th (E), the 7th (N), the 5th again (T), the 13th (Y) to form T.W.E.N.T.Y. and 20 is the double of a(2) = 10. Etc. %C A345715 We are allowed to use the same letter many times (like the 4th one, E, for instance) to form a new name. The sequence A345711 forbids such repetitions. %C A345715 No obvious pattern appears in the sequence, although the set of names is limited. %Y A345715 Cf. A131744, A345711, A345712, A345713, A345714. %K A345715 nonn,word %O A345715 1,1 %A A345715 _Eric Angelini_ and _Carole Dubois_, Jun 28 2021