OFFSET
2,1
COMMENTS
For a(n), Milnor 2011 Theorem 5 gives the formula
2^(2*n-2)*(2^(2*n-1)-1)*numerator(4*bernoulli(n)/n)
where bernoulli(n) = abs(Bernoulli(2*n)).
See A001676 for additional comments, references, and links.
REFERENCES
J. W. Milnor and J. D. Stasheff, Characteristic Classes, Princeton, 1974, p. 285.
LINKS
G. C. Greubel, Table of n, a(n) for n = 2..235
John W. Milnor, Differential Topology Forty-six Years Later, Notices Amer. Math. Soc. 58 (2011), 804-809 (see Theorem 5 and Table 3).
John W. Milnor, Spheres, Abel Prize lecture (video), 2011.
FORMULA
a(n) = 2^(2*n - 2) * (2^(2*n - 1) - 1) * abs(numerator(4*Bernoulli(2*n)/n)).
a(n) = A187595(4*n-1) for n > 1.
EXAMPLE
a(2) = 2^2 * (2^3 - 1) * abs(numerator(4 * Bernoulli(4)/2)) = 4 * 7 * abs(numerator(2 * (-1/30))) = 28
MATHEMATICA
Table[2^(2*n-2)*(2^(2*n-1)-1)*Abs[Numerator[4*BernoulliB[2*n]/n]], {n, 2, 17}]
PROG
(Magma) [2^(2*n-2)*(2^(2*n-1)-1)*Abs(Numerator(4*Bernoulli(2*n)/n)): n in [2..30]]; // G. C. Greubel, Jan 11 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonathan Sondow, Jun 15 2011
STATUS
approved