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A334745
Starting with a(1) = a(2) = 1, proceed in a square spiral, computing each term as the sum of diagonally adjacent prior terms.
2
1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 3, 2, 3, 1, 1, 3, 2, 3, 1, 1, 3, 3, 3, 3, 1, 1, 3, 3, 3, 3, 1, 1, 4, 3, 6, 3, 4, 1, 1, 4, 3, 6, 3, 4, 1, 1, 4, 4, 6, 6, 4, 4, 1, 1, 4, 4, 6, 6, 4, 4, 1, 1, 5, 4, 10, 6, 10, 4, 5, 1, 1, 5, 4, 10, 6
OFFSET
1,8
LINKS
Peter Kagey, Bitmap illustrating the parity of the first 2^22 terms. (Even and odd numbers are represented with black and white pixels respectively.)
FORMULA
Conjecture: a(2n-1) = A247976(n).
EXAMPLE
Spiral begins:
... 3---3---3---3---1
|
1---1---2---2---1 1
| | |
2 1---1---1 1 3
| | | | |
2 1 1---1 2 2
| | | |
1 1---2---1---1 3
| |
1---3---2---3---1---1
The last illustrated term above is a(35) = 3 = 2 + 1 because diagonally down-right is 2 and diagonally down-left is 1.
CROSSREFS
The x- and y-coordinates at n-th step are A174344 and A274923 respectively.
Sequence in context: A307017 A220424 A182907 * A323231 A175128 A359307
KEYWORD
nonn
AUTHOR
Alec Jones and Peter Kagey, May 09 2020
STATUS
approved