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 A371257 #19 Apr 01 2024 12:08:47 %S A371257 0,1,2,3,5,6,7,4,8,9,17,18,22,10,11,15,16,19,20,21,23,12,14,24,25,13, %T A371257 26,27,53,54,67,28,29,51,52,55,56,66,68,30,32,33,34,46,47,48,50,57,59, %U A371257 60,61,64,65,69,70,31,35,45,49,58,62,63,71,36,44,72,76 %N A371257 Irregular triangle T(n, k), n >= 0, k = 1..2^A005811(n), read by rows; the n-th row lists the numbers m such that A371256(m) = n. %C A371257 The n-th row has 2^A005811(n) terms. %C A371257 As a flat sequence, this is a permutation of the nonnegative integers, with inverse A371258. %H A371257 Rémy Sigrist, <a href="/A371257/b371257.txt">Table of n, a(n) for n = 0..6560</a> %H A371257 Rémy Sigrist, <a href="/A371257/a371257.gp.txt">PARI program</a> %H A371257 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %e A371257 Triangle T(n, k) begins: %e A371257 n n-th row %e A371257 -- -------------------------------------------------------------- %e A371257 0 0 %e A371257 1 1, 2 %e A371257 2 3, 5, 6, 7 %e A371257 3 4, 8 %e A371257 4 9, 17, 18, 22 %e A371257 5 10, 11, 15, 16, 19, 20, 21, 23 %e A371257 6 12, 14, 24, 25 %e A371257 7 13, 26 %e A371257 8 27, 53, 54, 67 %e A371257 9 28, 29, 51, 52, 55, 56, 66, 68 %e A371257 10 30, 32, 33, 34, 46, 47, 48, 50, 57, 59, 60, 61, 64, 65, 69, 70 %e A371257 11 31, 35, 45, 49, 58, 62, 63, 71 %e A371257 12 36, 44, 72, 76 %e A371257 13 37, 38, 42, 43, 73, 74, 75, 77 %e A371257 14 39, 41, 78, 79 %e A371257 15 40, 80 %e A371257 . %e A371257 Triangle T(n, k) begins, in ternary, with row indexes in binary: %e A371257 bin(n) n-th row in ternary %e A371257 ------ ---------------------------------------------- %e A371257 0 0 %e A371257 1 1, 2 %e A371257 10 10, 12, 20, 21 %e A371257 11 11, 22 %e A371257 100 100, 122, 200, 211 %e A371257 101 101, 102, 120, 121, 201, 202, 210, 212 %e A371257 110 110, 112, 220, 221 %e A371257 111 111, 222 %e A371257 1000 1000, 1222, 2000, 2111 %e A371257 1001 1001, 1002, 1220, 1221, 2001, 2002, 2110, 2112 %o A371257 (PARI) \\ See Links section. %Y A371257 See A371265 for a similar sequence. %Y A371257 Cf. A005811, A166242, A368229, A371256. %K A371257 nonn,base,tabf %O A371257 0,3 %A A371257 _Rémy Sigrist_, Mar 16 2024