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 A379927 #7 Jan 09 2025 08:48:18 %S A379927 1,2,3,4,5,6,7,8,9,10,19,18,28,17,11,26,37,16,29,20,15,12,25,46,24, %T A379927 101,27,110,55,14,39,200,23,13,33,299,22,38,389,34,47,32,41,59,21,36, %U A379927 398,479,30,49,102,111,488,45,54,497,569,120,35,201,44,63,210,31 %N A379927 Replacing each term of this sequence S with its digitsum produces a new sequence S' such that S and S' share the same succession of nonzero digits. %C A379927 The sequence starts with a(1) = 1 and is always extended with the smallest integer not yet present that doesn't lead to a contradiction. %C A379927 This sequence is a variant of A302656 ignoring zeros; this feature prevents the huge jumps seen in A302656. %H A379927 Rémy Sigrist, <a href="/A379927/b379927.txt">Table of n, a(n) for n = 1..10000</a> %H A379927 Rémy Sigrist, <a href="/A379927/a379927.gp.txt">PARI program</a> %e A379927 The first terms are: %e A379927 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 19, 18, 28, 17, 11, 26, 37, 16, 29, 20 %e A379927 The corresponding digitsums are: %e A379927 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 10, 9, 10, 8, 2, 8, 10, 7, 11, 2 %e A379927 Keeping only the nonzero digits we obtain: %e A379927 12345678911918281711263716292 %e A379927 and 123456789119182817112. %o A379927 (PARI) \\ See Links section. %Y A379927 Cf. A004719, A302656. %K A379927 nonn,base %O A379927 1,2 %A A379927 _Rémy Sigrist_, Jan 06 2025