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A356122
Number of Lucas divisors of the n-th Lucas number.
2
2, 1, 2, 3, 2, 2, 4, 2, 2, 4, 3, 2, 4, 2, 3, 5, 2, 2, 5, 2, 3, 5, 3, 2, 4, 3, 3, 5, 3, 2, 6, 2, 2, 5, 3, 4, 5, 2, 3, 5, 3, 2, 6, 2, 3, 7, 3, 2, 4, 3, 4, 5, 3, 2, 6, 4, 3, 5, 3, 2, 6, 2, 3, 7, 2, 4, 6, 2, 3, 5, 5, 2, 5, 2, 3, 7, 3, 4, 6, 2, 3, 6, 3, 2, 6, 4, 3, 5, 3, 2, 8, 4, 3, 5, 3, 4, 4, 2, 4, 7
OFFSET
0,1
LINKS
FORMULA
a(n) = A304092(A000032(n)).
PROG
(PARI) L(n)=fibonacci(n+1)+fibonacci(n-1); \\ A000032
isld(n) = { my(u1=1, u2=3, old_u1); if(n<=2, sign(n), while(n>u2, old_u1=u1; u1=u2; u2=old_u1+u2); (u2==n)); }; \\ A102460
nbld(n) = sumdiv(n, d, isld(d)); \\ A304092
a(n) = nbld(L(n));
(PARI) a(n) = if(n==1, return(1)); my(k=fibonacci(n+1)+fibonacci(n-1), c=0, x=2, y=1); while(x <= k, if(k%x == 0, c++); [x, y]=[y, x+y]); c; \\ Daniel Suteu, Aug 25 2022
CROSSREFS
Cf. A076984 (similar for Fibonacci numbers).
Sequence in context: A058071 A174961 A104889 * A290979 A117910 A275435
KEYWORD
nonn
AUTHOR
Michel Marcus, Jul 27 2022
STATUS
approved