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.

A342707 T(n, k) is the result of replacing 2's by k's in the hereditary base-2 expansion of n; square array T(n, k) read by antidiagonals upwards, n, k >= 0.

Original entry on oeis.org

0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 2, 2, 1, 0, 2, 1, 3, 3, 1, 0, 1, 2, 4, 4, 4, 1, 0, 2, 2, 5, 27, 5, 5, 1, 0, 0, 3, 6, 28, 256, 6, 6, 1, 0, 1, 1, 7, 30, 257, 3125, 7, 7, 1, 0, 0, 2, 8, 31, 260, 3126, 46656, 8, 8, 1, 0, 1, 2, 9, 81, 261, 3130, 46657, 823543, 9, 9, 1, 0
Offset: 0

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Author

Rémy Sigrist, Jun 04 2021

Keywords

Examples

			Array T(n, k) begins:
  n\k|  0  1   2   3     4      5       6        7          8           9
  ---+-------------------------------------------------------------------
    0|  0  0   0   0     0      0       0        0          0           0
    1|  1  1   1   1     1      1       1        1          1           1
    2|  0  1   2   3     4      5       6        7          8           9
    3|  1  2   3   4     5      6       7        8          9          10
    4|  1  1   4  27   256   3125   46656   823543   16777216   387420489
    5|  2  2   5  28   257   3126   46657   823544   16777217   387420490
    6|  1  2   6  30   260   3130   46662   823550   16777224   387420498
    7|  2  3   7  31   261   3131   46663   823551   16777225   387420499
    8|  0  1   8  81  1024  15625  279936  5764801  134217728  3486784401
    9|  1  2   9  82  1025  15626  279937  5764802  134217729  3486784402
   10|  0  2  10  84  1028  15630  279942  5764808  134217736  3486784410
		

Crossrefs

See A341907 for a similar sequence.

Programs

  • PARI
    T(n,k) = { my (v=0, e); while (n, n-=2^e=valuation(n,2); v+=k^T(e,k)); v }

Formula

T(n, n) = A343255(n).
T(n, 0) = A345021(n).
T(n, 1) = A000120(n).
T(n, 2) = n.
T(n, 3) = A222112(n-1).
T(0, k) = 0.
T(1, k) = 1.
T(2, k) = k.
T(3, k) = k + 1.
T(4, k) = k^k = A000312(k).
T(5, k) = k^k + 1 = A014566(k).
T(6, k) = k^k + k = A066068(k).
T(7, k) = k^k + k + 1 = A066279(k).
T(16, k) = k^k^k = A002488(k).
T(m + n, k) = T(m, k) + T(n, k) when m AND n = 0 (where AND denotes the bitwise AND operator).