1,1

The well-known integers very close to e^(pi sqrt n) for n=A003173(m) are of the form (12(k^2-1))^3+744. This sequence gives the rounded n-value corresponding to a given k.

See A138852 for links, references and more information.

Table of n, a(n) for n=1..66.

(PARI) A139388(n)=round(log(744+(12*(n^2-1))^3)/Pi)^2)

Cf. A138851-A138852, A003173, A014708, A056581 and references therein.

Sequence in context: A244433 A086109 A275116 * A300746 A301190 A301184

Adjacent sequences: A139385 A139386 A139387 * A139389 A139390 A139391

nonn,easy

M. F. Hasler, Apr 17 2008

approved