A126577 a(n) = numerator of the sum of reciprocals of the terms in n-th row of triangle A077581.

1, 4, 7, 176, 9, 133542, 103, 91072, 99527, 131023748, 7591, 300996993816, 88001, 1403843964196, 44094737, 10686452707072, 825533, 368070779365071896502, 2895701, 8653175044141052500, 81659533540907, 3080940707518158404

Offset

1,2

Links

Table of n, a(n) for n=1..22.

Example

Row 4 of triangle A077581 is (1,3,5,7).
So a(4) is the numerator of 1/1 +1/3 +1/5 + 1/7 = 176/105.

Mathematica

row[n_] := Take[Select[Range[n^2], GCD[ #, n] == 1 &], n]; Table[Numerator[Plus @@ (1/# &) /@ row[n]], {n, 23}] (* Ray Chandler, Dec 29 2006 *)

Crossrefs

Cf. A077581, A126578.

Sequence in context: A024054 A362857 A289381 * A236288 A348131 A073164

Adjacent sequences: A126574 A126575 A126576 * A126578 A126579 A126580

Keyword

frac,nonn

Author

Leroy Quet, Dec 28 2006

Extensions

Extended by Ray Chandler, Dec 29 2006

Status

approved