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.

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A293970 Number of sets of exactly eight nonempty words with a total of n letters over n-ary alphabet such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.

Original entry on oeis.org

10, 206, 1926, 13957, 85610, 476631, 2477550, 12289388, 58942808, 276126959, 1272626168, 5803545269, 26305047510, 118947441994, 538263144030, 2444159610896, 11163194878438, 51392032544011, 238939873029462, 1123916805738119, 5357138152220234, 25913264903132961
Offset: 21

Views

Author

Alois P. Heinz, Oct 20 2017

Keywords

Crossrefs

Column k=8 of A293815.
Cf. A000085.

Programs

  • Maple
    g:= proc(n) option remember; `if`(n<2, 1, g(n-1)+(n-1)*g(n-2)) end:
    b:= proc(n, i) option remember; series(`if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1)*binomial(g(i), j)*x^j, j=0..n/i))), x, 9)
        end:
    a:= n-> coeff(b(n$2), x, 8):
    seq(a(n), n=21..45);

Formula

a(n) = [x^n y^8] Product_{j>=1} (1+y*x^j)^A000085(j).

A293971 Number of sets of exactly nine nonempty words with a total of n letters over n-ary alphabet such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.

Original entry on oeis.org

45, 740, 7265, 54844, 355786, 2086218, 11402599, 59244154, 296592681, 1444795518, 6898985716, 32478508414, 151439118998, 702039301562, 3246061184641, 15011635714770, 69604533115983, 324297338323040, 1521325113273431, 7199243859471728, 34426802099939524
Offset: 25

Views

Author

Alois P. Heinz, Oct 20 2017

Keywords

Crossrefs

Column k=9 of A293815.
Cf. A000085.

Programs

  • Maple
    g:= proc(n) option remember; `if`(n<2, 1, g(n-1)+(n-1)*g(n-2)) end:
    b:= proc(n, i) option remember; series(`if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1)*binomial(g(i), j)*x^j, j=0..n/i))), x, 10)
        end:
    a:= n-> coeff(b(n$2), x, 9):
    seq(a(n), n=25..49);

Formula

a(n) = [x^n y^9] Product_{j>=1} (1+y*x^j)^A000085(j).

A293972 Number of sets of exactly ten nonempty words with a total of n letters over n-ary alphabet such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.

Original entry on oeis.org

120, 2010, 21082, 169846, 1173098, 7286181, 41993502, 228997683, 1198101638, 6074435686, 30073235682, 146248264684, 701957684114, 3338454463793, 15784582285468, 74407037119692, 350575594435412, 1654700449779204, 7840223330719670, 37363522942015498
Offset: 29

Views

Author

Alois P. Heinz, Oct 20 2017

Keywords

Crossrefs

Column k=10 of A293815.
Cf. A000085.

Programs

  • Maple
    g:= proc(n) option remember; `if`(n<2, 1, g(n-1)+(n-1)*g(n-2)) end:
    b:= proc(n, i) option remember; series(`if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1)*binomial(g(i), j)*x^j, j=0..n/i))), x, 11)
        end:
    a:= n-> coeff(b(n$2), x, 10):
    seq(a(n), n=29..53);

Formula

a(n) = [x^n y^10] Product_{j>=1} (1+y*x^j)^A000085(j).
Previous Showing 11-13 of 13 results.