A139040 Triangle read by rows: each row is an initial segment of the terms of A000930 followed by its reflection.

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 3, 2, 1, 1, 1, 1, 2, 3, 3, 2, 1, 1, 1, 1, 2, 3, 4, 3, 2, 1, 1, 1, 1, 2, 3, 4, 4, 3, 2, 1, 1, 1, 1, 2, 3, 4, 6, 4, 3, 2, 1, 1, 1, 1, 2, 3, 4, 6, 6, 4, 3, 2, 1, 1, 1, 1, 2, 3, 4, 6, 9, 6, 4, 3, 2, 1, 1, 1, 1, 2, 3, 4, 6, 9, 9, 6, 4, 3, 2, 1, 1

Offset: 1

Author

Roger L. Bagula and Gary W. Adamson, May 31 2008

Keywords

• nonn
• easy
• tabl

Examples

			Triangle begins:
{1},
{1, 1},
{1, 1, 1},
{1, 1, 1, 1},
{1, 1, 2, 1, 1},
{1, 1, 2, 2, 1, 1},
{1, 1, 2, 3, 2, 1, 1},
{1, 1, 2, 3, 3, 2, 1, 1},
{1, 1, 2, 3, 4, 3, 2, 1, 1},
{1, 1, 2, 3, 4, 4, 3, 2, 1, 1},
{1, 1, 2, 3, 4, 6, 4, 3, 2, 1, 1}
		

Links

• G. C. Greubel, Table of n, a(n) for the first 100 rows, flattened

Crossrefs

Cf. A139147, A000930. Row sums are in A238383.

Programs

Maple

A000930 := proc(n) coeftayl( 1/(1-x-x^3),x=0,n) ; end: A139040 := proc(n,m) A000930(min(m,n+1-m)) ; end: for n from 1 to 16 do for m from 1 to n do printf("%d,",A139040(n,m)) ; od: od: # R. J. Mathar, Jun 08 2008

Mathematica

a[-2]=0;a[-1]=1;a[0]=1;a[n_]:=a[n]=a[n-1]+a[n-3];(*A000930*)
g[n_,m_]:=If[m <= Floor[n/2],a[m],a[n-m]];w=Table[Table[g[n,m],{m,0,n}],{n,0,10}]; Flatten[w]

Extensions

Edited and corrected by N. J. A. Sloane, Jun 30 2008

Corrected by Philippe Deléham, Feb 25 2014