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A306745
Even bisection of A318256.
1
1, 2, 6, 6, 10, 6, 210, 2, 30, 210, 110, 30, 546, 14, 30, 462, 1190, 6, 51870, 70, 2310, 2310, 322, 210, 6630, 286, 330, 798, 290, 30, 930930, 1430, 1122, 82110, 70, 330, 21111090, 38038, 390, 210, 536690, 39270, 7489482, 10010, 62790, 4470510, 687610, 462
OFFSET
0,2
COMMENTS
The ratio sequence of a(n)/A006955(n) begins: 1,1,1,1,1,1,1,1,1,5,1,5,1,7,1,1,7,1,1,35, ...
This divisibility by A006955 was confirmed by Peter Luschny in the SeqFan mailing list.
LINKS
Jean-François Alcover, Table of n, a(n) for n = 0..1000
FORMULA
a(n) = (denominator of B(2n,x)) / (the squarefree kernel of 2n+1), where B(2n,x) is the 2n-th Bernoulli polynomial.
MATHEMATICA
sfk[n_] := Times @@ FactorInteger[n][[All, 1]];
a[n_] := (BernoulliB[2 n, x] // Together // Denominator)/sfk[2 n + 1];
Table[a[n], {n, 0, 60}]
CROSSREFS
Sequence in context: A021978 A141377 A006955 * A196053 A063210 A114718
KEYWORD
nonn
AUTHOR
STATUS
approved