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A215619
a(n) is the number of consecutive terms of A100071, beginning with index n, which are divisible by n.
1
4, 1, 6, 1, 8, 1, 4, 1, 12, 5, 14, 1, 4, 1, 18, 1, 20, 1, 4, 1, 24, 1, 6, 1, 4, 1, 30, 21, 32, 1, 12, 1, 8, 1, 38, 1, 14, 1, 42, 1, 44, 1, 6, 1, 48, 1, 8, 1, 4, 1, 54, 1, 6, 9, 4, 1, 60, 1, 62, 1, 4, 1, 6, 1, 68, 1, 4, 1, 72, 1, 74, 1, 4, 1, 12, 1, 80, 1, 4, 1
OFFSET
3,1
COMMENTS
a(n) = n+1 iff n is prime.
a(n) = 1 iff n in { A067315 }.
1 <= a(n) <= n+1.
{ n : a(2n)>1 } = { A058008 } \ { 1 }.
LINKS
MAPLE
b:= proc(n) b(n):= n * binomial(n-1, floor((n-1)/2)) end:
a:= proc(n) local k;
for k from 0 while irem(b(n+k), n)=0 do od; k
end:
seq (a(n), n=3..100); # Alois P. Heinz, Aug 17 2012
MATHEMATICA
b[n_] := n Binomial[n-1, Floor[(n-1)/2]];
a[n_] := Module[{k = 0}, While[Mod[b[n+k], n] == 0, k++]; k];
a /@ Range[3, 100] (* Jean-François Alcover, Nov 22 2020, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Aug 17 2012
STATUS
approved