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 1-4 of 4 results.

A085176 Transpose of A085178.

Original entry on oeis.org

1, 2, 3, 4, 5, 8, 6, 7, 13, 22, 9, 10, 18, 36, 64, 11, 12, 21, 50, 106, 196, 14, 15, 27, 59, 148, 328, 625, 16, 17, 32, 63, 176, 460, 1054, 2055, 19, 20, 35, 78, 190, 550, 1483, 3485, 6917, 23, 24, 41, 92, 195, 598, 1780, 4915, 11779, 23713, 25, 26, 46, 101, 238
Offset: 1

Views

Author

Antti Karttunen, Jun 18 2003

Keywords

Crossrefs

Inverse permutation: A085177.

A085179 Inverse permutation to A085178.

Original entry on oeis.org

1, 3, 2, 6, 5, 10, 9, 4, 15, 14, 21, 20, 8, 28, 27, 36, 35, 13, 45, 44, 19, 7, 55, 54, 66, 65, 26, 78, 77
Offset: 1

Views

Author

Antti Karttunen, Jun 18 2003

Keywords

A080237 Start with 1 and apply the process: k-th run is 1, 2, 3, ..., a(k-1)+1.

Original entry on oeis.org

1, 1, 2, 1, 2, 1, 2, 3, 1, 2, 1, 2, 3, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 1, 2, 3, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 1, 2, 3, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 3, 4, 5, 1, 2, 1, 2, 3, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 1, 2, 3, 1, 2, 1, 2
Offset: 1

Views

Author

Benoit Cloitre, Mar 18 2003

Keywords

Comments

Also a triangle collected from the Catalan generating tree, with row n containing A000108(n) terms and ending with n. Rows converge towards A007001, the "last" row. - Antti Karttunen, Jun 17 2003

Examples

			As an irregular triangle:
  1;
  1,2;
  1,2,1,2,3;
  1,2,1,2,3,1,2,1,2,3,1,2,3,4;
  ...
Sequence begins: 1,(1,2),(1,2),(1,2,3), ... where runs are between 2 parentheses. 5th run is (1,2) since a(4)=1 and sequence continues: 1,1,2,1,2,1,2,3,1,2....
G.f. = x + x^2 + 2*x^3 + x^4 + 2*x^5 + x^6 + 2*x^7 + 3*x^8 + x^9 + 2*x^10 + ...
		

Crossrefs

Cf. A000002, A007001. Positions of ones: A085223. The first occurrence of each n is at A014138(n). See A085178.

Programs

  • Haskell
    a080237 n k = a080237_tabf !! (n-1) !! (k-1)
    a080237_row n = a080237_tabf !! (n-1)
    a080237_tabf = [1] : f a080237_tabf where
       f [[]] =[]
       f (xs:xss) = concatMap (enumFromTo 1 . (+ 1)) xs : f xss
    a080237_list = concat a080237_tabf
    -- Reinhard Zumkeller, Jun 01 2015
  • Mathematica
    run[1] = {1}; run[k_] := run[k] = Range[ Flatten[ Table[run[j], {j, 1, k-1}]][[k-1]] + 1]; Table[run[k], {k, 1, 29}] // Flatten (* Jean-François Alcover, Sep 12 2012 *)
    NestList[ Flatten[# /. # -> Range[# + 1]] &, {1}, 5] // Flatten (* Robert G. Wilson v, Jun 24 2014 *)
  • PARI
    {a(n) = my(v, i, j, k); if( n<1, 0, v=vector(n); for(m=1, n, v[m]=k++; if( k>j, j=v[i++]; k=0)); v[n])}; /* Michael Somos, Jun 24 2014 */
    

Formula

It seems that Sum_{k=1..n} a(k) = C*n*log(log(n)) + O(n*log(log(n))) with C = 0.6....
a(n) = A007814(A014486(n)) (i.e., number of trailing zeros in A063171(n)).

A085180 Array A(x,y) giving the position of the y-th x in A007001 listed by rising antidiagonals.

Original entry on oeis.org

1, 2, 3, 5, 4, 6, 14, 10, 7, 8, 42, 28, 13, 9, 11, 132, 84, 37, 19, 12, 15, 429, 264, 112, 41, 24, 16, 17, 1430, 858, 354, 126, 56, 27, 18, 20, 4862, 2860, 1155, 402, 131, 70, 33, 21, 22, 16796, 9724, 3861, 1320, 422, 174, 79, 36, 23, 25, 58786, 33592, 13156, 4433
Offset: 1

Views

Author

Antti Karttunen, Jun 18 2003

Keywords

Comments

Read by upwards antidiagonals as A(1,1), A(2,1), A(1,2), A(3,1), A(2,2), A(1,3), etc.

Examples

			In A007001 each n occurs for the first time at position Cat(n), thus A(x,1) (the first row) is A000108.
		

Crossrefs

Variant: A085178.
Inverse permutation: A085181.
First row: A000108, second row: A068875 apart from initial terms, first column: A085197, central diagonal: A001453.
Showing 1-4 of 4 results.