A140957 a(n) = A140951(n+1) - A140951(n).

2, 2, 1, 4, 1, 1, 8, 1, 1, 2, 16, 2, 1, 1, 4, 32, 4, 1, 1, 2, 8, 64, 8, 2, 1, 1, 4, 16, 128, 16, 4, 1, 1, 2, 8, 32, 256, 32, 8, 2, 1, 1, 4, 16, 64, 512, 64, 16, 4, 1

Offset

0,1

Comments

All terms belong to A000079.

Note that the positions of the first occurrences of 4, 8, 16, 32, 64, ... are 3, 6, 10, 15, 21, ...

So a(n) can be displayed as a triangle (hence the tabl keyword), with row sums: 2, 3, 6, 12, 24, 48, ... = A042950.

2;

2, 1;

4, 1, 1;

8, 1, 1, 2;

It can also be displayed as an irregular table, with length distribution: 1, 1, 3, 3, 5, 5, 7, 7, 9, 9 (doubled A005408) to get palindromic lines.

2;

2;

1, 4, 1;

1, 8, 1;

1, 2, 16, 2, 1;

1, 4, 32, 4, 1;

with row sums: 2, 2, 6, 10, 22, 42, 66, 170, 342, 682, ... = A078008(n+2) = 2*A001045(n+1).

Links

Table of n, a(n) for n=0..49.

Crossrefs

Cf. A000079, A042950, A140951, A140643.

Sequence in context: A106641 A191785 A320500 * A197250 A275578 A112085

Adjacent sequences: A140954 A140955 A140956 * A140958 A140959 A140960

Keyword

nonn,tabl

Author

Paul Curtz, Jul 26 2008

Extensions

Edited by Michel Marcus, Jan 11 2012

Status

approved