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.

Previous Showing 11-19 of 19 results.

A213291 Number of n-length words w over ternary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.

Original entry on oeis.org

1, 3, 9, 18, 36, 74, 165, 367, 869, 2074, 5168, 13026, 33749, 88368, 235389, 632324, 1717202, 4693604, 12921864, 35751336, 99416633, 277527448, 777659128, 2185854247, 6162168724, 17416305904, 49342480077, 140094014788, 398558682310, 1135962971848
Offset: 0

Views

Author

Alois P. Heinz, Jun 08 2012

Keywords

Examples

			a(0) = 1: the empty word.
a(1) = 3: a, b, c for alphabet {a,b,c}.
a(2) = 9: aa, ab, ac, ba, bb, bc, ca, cb, cc.
a(3) = 18: aaa, aab, aac, aba, abc, aca, acb, baa, bac, bbb, bbc, bca, bcb, caa, cab, cba, cbb, ccc.
		

Crossrefs

Column k=3 of A213276.

A213292 Number of n-length words w over 4-ary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.

Original entry on oeis.org

1, 4, 16, 46, 118, 276, 712, 1805, 4895, 13280, 37993, 109386, 328219, 992413, 3101399, 9764376, 31580645, 102797899, 342075208, 1144125506, 3896297053, 13319243655, 46206520968, 160729837020, 565901313043, 1996113320841, 7111795754941, 25369213794266
Offset: 0

Views

Author

Alois P. Heinz, Jun 08 2012

Keywords

Crossrefs

Column k=4 of A213276.

A213293 Number of n-length words w over 5-ary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.

Original entry on oeis.org

1, 5, 25, 95, 315, 895, 2535, 7280, 21562, 64924, 201975, 640915, 2095019, 6978713, 23859310, 82982260, 295202798, 1066467105, 3928481530, 14672457970, 55722273963, 214254166369, 835669136725, 3295598362466, 13156401722237, 53038076210255, 216053087821059
Offset: 0

Views

Author

Alois P. Heinz, Jun 08 2012

Keywords

Crossrefs

Column k=5 of A213276.

A213294 Number of n-length words w over 6-ary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.

Original entry on oeis.org

1, 6, 36, 171, 711, 2506, 8151, 25781, 83728, 273248, 916966, 3121506, 10934875, 38945256, 142403783, 529393936, 2014819829, 7790840332, 30758499541, 123255094820, 503078455794, 2081817569353, 8756613613322, 37300624224737, 161213532001916, 704851308055768
Offset: 0

Views

Author

Alois P. Heinz, Jun 08 2012

Keywords

Crossrefs

Column k=6 of A213276.

A213295 Number of n-length words w over 7-ary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.

Original entry on oeis.org

1, 7, 49, 280, 1414, 6104, 23527, 83916, 296268, 1050777, 3771418, 13717679, 50861266, 191950441, 739460834, 2901202157, 11612278801, 47307362988, 196385040929, 828929230122, 3560359729835, 15531007871015, 68843517673532, 309567264833019, 1412620935530761
Offset: 0

Views

Author

Alois P. Heinz, Jun 08 2012

Keywords

Crossrefs

Column k=7 of A213276.

A213296 Number of n-length words w over 8-ary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.

Original entry on oeis.org

1, 8, 64, 428, 2556, 13224, 60600, 250062, 977026, 3754472, 14486158, 56109736, 220213038, 875120922, 3539254104, 14534439529, 60794185555, 258385808222, 1118113946883, 4915589687030, 21983704654711, 99825770573061, 460645444681024, 2156595097630195
Offset: 0

Views

Author

Alois P. Heinz, Jun 08 2012

Keywords

Crossrefs

Column k=8 of A213276.

A213297 Number of n-length words w over 9-ary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.

Original entry on oeis.org

1, 9, 81, 621, 4293, 26061, 140517, 676155, 2990967, 12602451, 52359693, 216954441, 901911273, 3778512489, 16012113225, 68739345546, 299377174968, 1323228682218, 5939020708851, 27063683050245, 125241936884631, 588324477445971, 2805460966739493
Offset: 0

Views

Author

Alois P. Heinz, Jun 08 2012

Keywords

Crossrefs

Column k=9 of A213276.

A213298 Number of n-length words w over 10-ary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.

Original entry on oeis.org

1, 10, 100, 865, 6805, 47590, 297595, 1662160, 8418649, 39598078, 178880725, 795246055, 3519278713, 15573399301, 69314501935, 311040898945, 1411268823196, 6478030875460, 30129403442530, 141971859499360, 678365095896001, 3285531463054108, 16137537771997720
Offset: 0

Views

Author

Alois P. Heinz, Jun 08 2012

Keywords

Crossrefs

Column k=10 of A213276.

A321704 Number of words w of length n over an n-ary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.

Original entry on oeis.org

1, 1, 4, 18, 118, 895, 8151, 83916, 977026, 12602451, 178880725, 2766415036, 46314488705, 834067614601, 16074694453741, 330017679352180, 7188779521480810
Offset: 0

Views

Author

Alois P. Heinz, Nov 17 2018

Keywords

Examples

			a(3) = 18: aaa, aab, aac, aba, abc, aca, acb, baa, bac, bbb, bbc, bca, bcb, caa, cab, cba, cbb, ccc.
		

Crossrefs

Main diagonal of A213276.

Programs

  • Maple
    h:= proc(n, k, m, l) option remember;
          `if`(n=0 and k=0, b(l), `if`(k=0 or n>0 and n1     then for j from i+1 to nops(l) do
          if l[i]<=l[j] then return false
        elif l[j]>0     then break
          fi od fi; true
        end:
    a:= n-> h(n$2, 0, []):
    seq(a(n), n=0..10);  # Alois P. Heinz, Mar 29 2020
  • Mathematica
    h[n_, k_, m_, l_] := h[n, k, m, l] = If[n == 0 && k === 0, b[l], If[k == 0 || n > 0 && n < m, 0, Sum[h[n - j, k - 1, Max[m, j], Join[{j}, l]], {j, Max[1, m], n}] + h[n, k - 1, m, Join[{0}, l]]]];
    b[l_] := b[l] = If[Complement[l, {0}] == {}, 1, Sum[If[g[l, i], b[ReplacePart[l, i -> l[[i]] - 1]], 0], {i, 1, Length[l]}]];
    g[l_, i_] := Module[{j}, If[l[[i]] < 1, Return[False], If[l[[i]] > 1, For[j = i + 1, j <= Length[l], j++, If[l[[i]] <= l[[j]], Return[False], If[l[[j]] > 0, Break[]]]]]]; True];
    a[n_] := h[n, n, 0, {}];
    Table[Print[n, " ", a[n]]; a[n], {n, 0, 15}] (* Jean-François Alcover, Jun 01 2022, after Alois P. Heinz *)

Formula

a(n) = A213276(n,n).
Previous Showing 11-19 of 19 results.