A082485 Numbers n such that 1/(2-s(n)) is an integer where s(k)=sum(i=1,k,1/3^floor(sqrt(i))).

3, 11, 21, 33, 47, 63, 83, 105, 129, 155, 183, 213, 245, 279, 315, 353, 393, 435, 479, 525, 573, 623, 675, 731, 789, 849, 911, 975, 1041, 1109, 1179, 1251, 1325, 1401, 1479, 1559, 1641, 1725, 1811, 1899, 1989

Offset

1,1

Comments

For any rational x=p/q > 1: L(x)=sum(i>=1,1/x^floor(sqrt(i))) is rational; i.e. L(4)=11/9, L(5)=7/8, L(7/3)=27/8.... L(x)=1 for an irrational value, namely : x=5/2+sqrt(17)/2.

Links

Table of n, a(n) for n=1..41.

Formula

s(a(n))=2-1/3^n

Crossrefs

Sequence in context: A031239 A088619 A031318 * A322595 A317298 A064568

Adjacent sequences: A082482 A082483 A082484 * A082486 A082487 A082488

Keyword

nonn

Author

Benoit Cloitre, Apr 27 2003

Status

approved