A119930 Sum of the numbers of the matrix A111490 along a boustrophedon path: a11, a11+a12, a11+a12+a21, etc.

1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 13, 15, 18, 20, 21, 22, 23, 24, 27, 29, 30

Offset

0,2

References

G. Balzarotti and P. P. Lava, Le sequenze di numeri interi, Hoepli, 2008, p. 60.

Links

Table of n, a(n) for n=0..20.

Example

If we rewrite the matrix putting on the top the upper left edge and then we sum the numbers following a boustrophedon path we have:
.............1.\
..........._____\
........../1...1.
........./_________
.........1...2...1.\
......______________\
...../.1...2...1...1.
..../__________________
.....1...2...3...2...1.\
..______________________\
..1...2...3...1...1...1.
then
1, 1+1, 1+1+1, 1+1+1+1, 1+1+1+1+2, 1+1+1+1+2+1, 1+1+1+1+2+1+1, 1+1+1+1+2+1+1+1, 1+1+1+1+2+1+1+1+2, 1+1+1+1+2+1+1+1+2+1, ...
That is 1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 13, 15, 18, 20, etc.

Crossrefs

Cf. A119931.

Sequence in context: A376665 A001959 A263135 * A173552 A188010 A350349

Adjacent sequences: A119927 A119928 A119929 * A119931 A119932 A119933

Keyword

nonn,easy

Author

Paolo P. Lava and Giorgio Balzarotti, May 30 2006

Status

approved