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A356387
a(n) is the product of all parts in negaFibonacci representation of n.
2
1, 1, 2, 2, -5, 5, 5, 10, 10, 39, -39, -39, -13, 13, 13, 26, 26, -65, 65, 65, 130, 130, -816, 816, 816, 272, -272, -272, -544, -544, 102, -102, -102, -34, 34, 34, 68, 68, -170, 170, 170, 340, 340, 1326, -1326, -1326, -442, 442, 442, 884, 884, -2210, 2210, 2210
OFFSET
0,3
COMMENTS
a(0) = 1 for the empty product.
See A273156 and A356388 for similar sequences.
EXAMPLE
For n = 11:
- using F(-k) = A039834(k):
- 11 = F(-1) + F(-4) + F(-7),
- so a(11) = F(-1) * F(-4) * F(-7) = 1 * -3 * 13 = -39.
PROG
(PARI) a(n) = { my (v=1); while (n, my (neg=0, pos=0, f); for (e=0, oo, f=fibonacci(-1-e); if (f<0, neg+=f, pos+=f); if (neg <=n && n <= pos, v*=f; n-=f; break))); return (v) }
CROSSREFS
KEYWORD
sign,base
AUTHOR
Rémy Sigrist, Aug 05 2022
STATUS
approved