A128270 a(n) = the numerator of b(n): {b(n)} is such that the continued fraction (of rational terms) [b(1);b(2),...,b(n)] equals the n-th prime, for every positive integer n.

2, 1, -3, 4, -3, 12, -3, 48, -3, 320, -3, 512, -135, 256, -243, 5120, -243, 8192, -27, 5120, -27, 2048, -135, 5120, -1701, 8192, -2187, 4096, -2187, 1024, -6561, 1792, -1215, 25088, -243, 62720, -27, 313600, -27, 1568000, -243, 2508800, -243, 6272000

Offset

1,1

Links

Diana Mecum, Table of n, a(n) for n = 1..500

Example

b(n): 2, 1, -3/2, 4, -3/4, 12, -3/16,...
The 4th prime, 7, equals [b(1);b(2),b(3),b(4)] = 2 +1/(1 +1/(-3/2 +1/4)).
The 5th prime, 11, equals [b(1);b(2),b(3),b(4),b(5)] = 2 +1/(1 +1/(-3/2 +1/(4 -4/3))).

Crossrefs

Cf. A128271.

Sequence in context: A002124 A097564 A345233 * A367860 A151550 A097003

Adjacent sequences: A128267 A128268 A128269 * A128271 A128272 A128273

Keyword

frac,sign

Author

Leroy Quet, Feb 22 2007

Extensions

More terms from Diana L. Mecum, Jun 24 2007

Status

approved