A081971 Consider the harmonic progression 1,1/2,1/3,1/4,1/5,..., group the terms such that the n-th group contains n members like this (1/1),(1/2,1/3),(1/4,1/5,1/6), (1/7,1/8,1/9,1/10),... a(n) = the numerator of the reduced rational sum of the terms of the n-th group.

1, 5, 37, 1207, 7793, 532541, 35036093, 419218787, 98431469723, 14642854403167, 6408932966879, 4075936031956831, 504163702484694137, 78452289445098136367, 9442422052170405158543, 711841627568479091422201

Offset

1,2

Comments

Equivalently, numerator of sum_{i=n(n-1)/2+1..n(n+1)/2} 1/i.

Links

Table of n, a(n) for n=1..16.

Prog

(PARI) nsn(n) = numerator(sum(i = n*(n-1)/2+1, n*(n+1)/2, 1/i));  \\ Michel Marcus, Aug 29 2013

Crossrefs

Denominator is in A082681.

Sequence in context: A166851 A090439 A089795 * A350966 A086877 A372839

Adjacent sequences: A081968 A081969 A081970 * A081972 A081973 A081974

Keyword

nonn,frac

Author

Amarnath Murthy, Apr 03 2003

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 08 2003

Status

approved