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.

Showing 1-3 of 3 results.

A348357 Square array T(n, k), n, k > 0, read by antidiagonal upwards; the k-th column contains, in ascending order, the integers m such that A348331(m) = k.

Original entry on oeis.org

1, 2, 4, 3, 5, 7, 6, 9, 8, 10, 12, 18, 15, 11, 13, 24, 36, 30, 21, 14, 16, 48, 72, 60, 42, 27, 17, 19, 96, 144, 120, 84, 54, 33, 20, 22, 192, 288, 240, 168, 108, 66, 39, 23, 25, 384, 576, 480, 336, 216, 132, 78, 45, 26, 28, 768, 1152, 960, 672, 432, 264, 156, 90, 51, 29, 31
Offset: 1

Views

Author

Rémy Sigrist, Oct 14 2021

Keywords

Comments

When interpreted as a flat array, we have a permutation of the positive integers.

Examples

			Array T(n, k) begins:
  n\k|    1     2     3     4     5     6     7     8     9    10
  ---+-----------------------------------------------------------
    1|    1     4     7    10    13    16    19    22    25    28
    2|    2     5     8    11    14    17    20    23    26    29
    3|    3     9    15    21    27    33    39    45    51    57
    4|    6    18    30    42    54    66    78    90   102   114
    5|   12    36    60    84   108   132   156   180   204   228
    6|   24    72   120   168   216   264   312   360   408   456
    7|   48   144   240   336   432   528   624   720   816   912
    8|   96   288   480   672   864  1056  1248  1440  1632  1824
    9|  192   576   960  1344  1728  2112  2496  2880  3264  3648
   10|  384  1152  1920  2688  3456  4224  4992  5760  6528  7296
		

Crossrefs

Programs

  • PARI
    See Links section.

Formula

Sum_{i = 1..n-1} T(i, k) <= T(n, k).
T(n, 1) = A098011(n+1).

A348330 Lexicographically earliest sequence of positive integers such that for any n > 0, the sum of the indices k < n such that a(k) = a(n) is strictly less than n.

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 3, 1, 2, 4, 4, 5, 5, 3, 6, 1, 6, 2, 7, 7, 8, 4, 8, 9, 9, 5, 10, 3, 10, 11, 11, 1, 6, 12, 12, 2, 13, 13, 14, 7, 14, 15, 15, 4, 8, 16, 16, 17, 17, 9, 18, 5, 18, 19, 19, 3, 10, 20, 20, 21, 21, 11, 22, 1, 22, 6, 23, 23, 24, 12, 24, 2, 25, 25, 26
Offset: 1

Views

Author

Rémy Sigrist, Oct 13 2021

Keywords

Comments

Every integer appears infinitely many times.
See table A348356 where the integers are arranged according to the present sequence.

Crossrefs

Programs

  • PARI
    s=vector(25); for (n=1, 75, for (k=1, oo, if (s[k]
    				

Formula

a(n) = 1 iff n is a power of 2 (A000079).

A348331 Lexicographically earliest sequence of positive integers such that for any n > 0, the sum of the indices k < n such that a(k) = a(n) is less than or equal to n.

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 3, 3, 2, 4, 4, 1, 5, 5, 3, 6, 6, 2, 7, 7, 4, 8, 8, 1, 9, 9, 5, 10, 10, 3, 11, 11, 6, 12, 12, 2, 13, 13, 7, 14, 14, 4, 15, 15, 8, 16, 16, 1, 17, 17, 9, 18, 18, 5, 19, 19, 10, 20, 20, 3, 21, 21, 11, 22, 22, 6, 23, 23, 12, 24, 24, 2, 25, 25, 13
Offset: 1

Views

Author

Rémy Sigrist, Oct 13 2021

Keywords

Comments

Every integer appears infinitely many times.
See table A348357 where the integers are arranged according to the present sequence.

Crossrefs

Programs

  • PARI
    s=vector(25); for (n=1, 75, for (k=1, oo, if (s[k]<=n, print1 (k", "); s[k]+=n; break)))

Formula

a(n) = 1 iff n belongs to A098011.
Showing 1-3 of 3 results.