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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A126027 Row lengths for A333867.

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 3, 4, 5, 6, 7, 7, 8, 11, 15, 18, 20, 23, 25, 30, 38, 49, 62, 77, 94, 110, 129, 149, 172, 195, 218, 241, 266, 293, 323, 356, 389, 424, 461, 500, 545, 593, 641, 688, 737, 787, 839, 896, 957, 1021, 1085, 1152, 1219, 1291, 1368, 1447, 1527, 1611, 1697
Offset: 1

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Author

Keywords

Crossrefs

Programs

Formula

a(n+1) = max_{k=1..a(n)} A333867(n,k).

A174382 T(1,0)=0 and for n > 1, T(n,k) is the number of k's in rows 1 to n - 1.

Original entry on oeis.org

0, 1, 1, 1, 1, 3, 1, 4, 0, 1, 2, 6, 0, 1, 1, 3, 8, 1, 1, 1, 0, 1, 4, 12, 1, 2, 1, 0, 1, 0, 1, 6, 16, 2, 2, 2, 0, 1, 0, 1, 0, 0, 0, 1, 11, 19, 5, 2, 2, 0, 2, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 19, 22, 8, 2, 2, 1, 2, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 27, 28, 11, 2, 2, 1, 2, 0, 2, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 2, 0, 0, 1
Offset: 1

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Author

Keywords

Comments

Construction as in A333867 but starting with a 0 and including a count of 0s at the start of each row. [Edited by Peter Munn, Oct 11 2022]
See A342585 for a similarly defined sequence that has been analyzed more and has lists of other related sequences. - Peter Munn, Oct 08 2022

Examples

			0;
1; # one zero
1,1; # one zero, one one
1,3; # one zero, three ones
1,4,0,1; # one zero, four ones, zero twos, one three
		

Crossrefs

Cf. A240508 (row lengths).

Programs

  • Haskell
    import Data.List (sort, group)
    a174382 n k = a174382_tabf !! (n-1) !! k
    a174382_row n = a174382_tabf !! (n-1)
    a174382_tabf = iterate f [0] where
       f xs = g (xs ++ [0, 0 ..]) [0..] (map head zs) (map length zs)
         where g   _ [] = []
               g (u:us) (k:ks) hs'@(h:hs) vs'@(v:vs)
                 | k == h = u + v : g us ks hs vs
                 | k /= h = u : g us ks hs' vs'
               zs = group $ sort xs
    -- Reinhard Zumkeller, Apr 06 2014
  • Maple
    b:= proc(n) option remember; `if`(n<1, 0, b(n-1)+add(x^i, i=T(n))) end:
    T:= proc(n) option remember; `if`(n=1, 0, (p->
          seq(coeff(p, x, i), i=0..degree(p)))(b(n-1)))
        end:
    seq(T(n), n=1..12);  # Alois P. Heinz, Aug 25 2025
Showing 1-2 of 2 results.