cp's OEIS Frontend

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.

A368239 Irregular table of nonnegative integers T(n, k), n >= 0, k = 1..A080100(n), read by rows; the 1's in the binary expansion of n exactly match the 1's in the balanced ternary expansions of the terms in the n-th row.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 8, 9, 7, 10, 11, 12, 13, 14, 15, 17, 18, 23, 24, 26, 27, 16, 19, 25, 28, 20, 21, 29, 30, 22, 31, 32, 33, 35, 36, 34, 37, 38, 39, 40, 41, 42, 44, 45, 50, 51, 53, 54, 68, 69, 71, 72, 77, 78, 80, 81, 43, 46, 52, 55, 70, 73, 79, 82, 47, 48, 56, 57, 74, 75, 83, 84
Offset: 0

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Author

Rémy Sigrist, Dec 18 2023

Keywords

Comments

As a flat sequence, this is a permutation of the nonnegative integers with inverse A368240.

Examples

			Table T(n, k) begins:
    0;
    1;
    2, 3;
    4;
    5, 6, 8, 9;
    7, 10;
    11, 12;
    13;
    14, 15, 17, 18, 23, 24, 26, 27;
    16, 19, 25, 28;
    20, 21, 29, 30;
    22, 31;
    32, 33, 35, 36;
    34, 37;
    38, 39;
    40;
    ...
		

Crossrefs

See A368225 for a similar sequence.

Programs

  • PARI
    row(n) = { my (r = [0], b = binary(n)); for (k = 1, #b, r = [3*v+b[k]|v<-r]; if (b[k]==0, r = concat(r, [v-1|v<-r]););); Set(r); }

Formula

T(n, 1) = A147991(n) for any n > 0.
T(n, A080100(n)) = A005836(n + 1).
A343228(T(n, k)) = n.