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A119931 Sum of the numbers of the matrix A111490 along a boustrophedon path: a11, a11+a21, a11+a21+a21, etc. 1
1, 2, 3, 4, 6, 7, 8, 10, 11, 12, 13, 15, 18, 20, 21, 22, 24, 27, 28, 29, 30 (list; graph; refs; listen; history; text; internal format)
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

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Last modified March 19 23:02 EDT 2019. Contains 321343 sequences. (Running on oeis4.)