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A355339
a(n) is the number of central even terms in the n-th row of triangle A355320; a(0) = 0.
2
0, 3, 1, 3, 3, 7, 1, 3, 5, 3, 5, 11, 3, 11, 1, 3, 5, 7, 7, 3, 5, 7, 9, 19, 7, 3, 5, 19, 3, 11, 1, 3, 5, 7, 9, 11, 13, 11, 7, 3, 5, 7, 9, 11, 13, 15, 17, 35, 15, 11, 7, 3, 5, 7, 9, 35, 7, 3, 5, 19, 3, 11, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 23, 19, 15
OFFSET
0,2
LINKS
FORMULA
Conjecture: a(n) = 1 iff n > 0 and n belongs to A000918.
EXAMPLE
The first terms, alongside the corresponding rows of A355320, are:
n a(n) n-th row of A355320
- ---- -------------------------------------------------------------
0 0 1
1 3 1 (0 0 0) 1
2 1 1 0 0 1 (2) 1 0 0 1
3 3 1 0 0 2 3 (2 0 2) 3 2 0 0 1
4 3 1 0 0 3 4 3 1 (6 8 6) 1 3 4 3 0 0 1
5 7 1 0 0 4 5 4 3(12 16 12 6 12 16 12) 3 4 5 4 0 0 1
PROG
(PARI) { rr = 0; r = 1; for (n=0, 76, print1 (max(0, 2*valuation(r >> (2*n), 2)-1)", "); [rr, r] = [r, bitxor(bitxor(r, r<<4), bitxor(rr<<3, rr<<5))]) }
CROSSREFS
Sequence in context: A173465 A151837 A356354 * A331856 A163381 A373886
KEYWORD
nonn
AUTHOR
Rémy Sigrist, Jun 29 2022
STATUS
approved