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.

A368225 Irregular table of nonnegative integers read by rows: the 1's in the binary expansion of n exactly match the nonzero digits in the balanced ternary expansions of the terms in the n-th row.

Original entry on oeis.org

0, 1, 3, 2, 4, 9, 8, 10, 6, 12, 5, 7, 11, 13, 27, 26, 28, 24, 30, 23, 25, 29, 31, 18, 36, 17, 19, 35, 37, 15, 21, 33, 39, 14, 16, 20, 22, 32, 34, 38, 40, 81, 80, 82, 78, 84, 77, 79, 83, 85, 72, 90, 71, 73, 89, 91, 69, 75, 87, 93, 68, 70, 74, 76, 86, 88, 92, 94
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 A368226 and infinitely many fixed points (see Formula section).
Row 0 has one term, and for n > 0, row n has A048896(n-1) terms.
For any n >= 0, row n ends with A005836(n+1).

Examples

			Table T(n, k) begins:
    0;
    1;
    3;
    2, 4;
    9;
    8, 10;
    6, 12;
    5, 7, 11, 13;
    27;
    26, 28;
    24, 30;
    23, 25, 29, 31;
    18, 36;
    17, 19, 35, 37;
    15, 21, 33, 39;
    14, 16, 20, 22, 32, 34, 38, 40;
    81;
    ...
		

Crossrefs

See A368229 and A368239 for similar sequences.

Programs

  • PARI
    row(n) = { my (r = [sign(n)], b = binary(n)); for (k = 2, #b, r = [3*v+b[k]|v<-r]; if (b[k], r = concat(r, [v-2|v<-r]););); Set(r); }

Formula

A343231(T(n, k)) = n.
a(m) = m for any m in A003462.