A074798 Floor of S*n^2, where S equals sum of reciprocal terms of this same sequence.

1, 5, 13, 23, 36, 52, 72, 94, 119, 147, 178, 211, 248, 288, 331, 376, 425, 476, 531, 588, 649, 712, 778, 847, 919, 994, 1072, 1153, 1237, 1324, 1414, 1507, 1602, 1701, 1803, 1907, 2014, 2125, 2238, 2354, 2474, 2596, 2721, 2849, 2980, 3114, 3251, 3391, 3533

Offset

1,2

Links

Table of n, a(n) for n=1..49.

Formula

a(n) = floor(S*n^2), where S = Sum_{k>=1} 1/a(k).

Example

a(10) = 147 because a(10) = floor(S*10^2), where S = 1/1 + 1/5 + 1/13 + 1/23 + 1/36 + 1/52 + 1/72 +... + 1/a(k) +... {k=1..inf}.
S = 1.471869231468455847281... This should be good to about 20 digits. - David Einstein

Crossrefs

Sequence in context: A125830 A049882 A108195 * A031336 A099958 A213483

Adjacent sequences: A074795 A074796 A074797 * A074799 A074800 A074801

Keyword

nonn,easy

Author

Paul D. Hanna, Sep 08 2002

Status

approved