A119931 Sum of the numbers of the matrix A111490 along a boustrophedon path: a11, a11+a21, a11+a21+a21, etc.

1, 2, 3, 4, 6, 7, 8, 10, 11, 12, 13, 15, 18, 20, 21, 22, 24, 27, 28, 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+2, 1+1+1+1+2+1+1+2+1, 1+1+1+1+2+1+1+2+1+1, ...
That is 1, 2, 3, 4, 6, 7, 8, 10, 11, 12, 13, 15, 18, 20, etc.

Crossrefs

Cf. A119930.

Sequence in context: A039149 A039081 A195128 * A129989 A187572 A184478

Adjacent sequences: A119928 A119929 A119930 * A119932 A119933 A119934

Keyword

nonn,easy

Author

Paolo P. Lava and Giorgio Balzarotti, May 30 2006

Status

approved