A055087 Integers 0..n then 0..n then 0..n+1 then 0..n+1 etc.

0, 0, 0, 1, 0, 1, 0, 1, 2, 0, 1, 2, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 0, 1, 2, 3, 4, 5, 6, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1

Offset

0,9

Comments

Second column in the monotonic justified array of all positive generalized Fibonacci sequences (A160271). see also A199474. - Casey Mongoven, Nov 06 2011

Can also be seen as an irregular triangle with duplicated rows of A002262. - Reinhard Zumkeller, Jul 14 2015

Links

Reinhard Zumkeller, Rows n = 0..120 of triangle, flattened

Michael Somos, Sequences used for indexing triangular or square arrays

Example

0; 0; 0,1; 0,1; 0,1,2; 0,1,2; 0,1,2,3; 0,1,2,3; ...

Mathematica

With[{nn=10}, Flatten[Table[{Range[0, n], Range[0, n]}, {n, 0, nn}]]] (* Harvey P. Dale, May 30 2015 *)

Prog

(PARI) {a(n) = (1 + 4*n - sqr( floor( sqrt( 1 + 4*n)))) \ 4}
(Haskell)
import Data.List (transpose)
a055087 n k = a055087_tabf !! n !! k
a055087_row n = a055087_tabf !! n
a055087_tabf = concat $ transpose [a002262_tabl, a002262_tabl]
a055087_list = concat a055087_tabf
-- Reinhard Zumkeller, Jul 14 2015

Crossrefs

Cf. A002262.

Sequence in context: A096771 A129714 A022333 * A025685 A194515 A163325

Adjacent sequences: A055084 A055085 A055086 * A055088 A055089 A055090

Keyword

nonn,easy,tabf,changed

Author

Michael Somos, Jun 13 2000

Status

approved