A126695 Numbers that can be expressed as the ratio between the product and the sum of n consecutive numbers with n>1.

1, 5, 8, 16, 20, 21, 33, 36, 40, 56, 65, 85, 96, 120, 133, 161, 176, 180, 208, 224, 225, 261, 280, 320, 341, 385, 408, 432, 456, 481, 533, 560, 616, 645, 705, 736, 756, 800, 833, 901, 936, 1008, 1045, 1120, 1121, 1152, 1160, 1232, 1240

Offset

1,2

Links

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

Formula

Number = Product_{i=a..a+n-1} i / Sum_{i=a..a+n-1} i with a, n > 1

Integer values of (n+1)*binomial(a+n,a-1)/Sum_{i=0..n-1}(a+i) with a, n > 1

Example

224 = 4*5*6*7*8/(4+5+6+7+8)
225 = 25*26*27/(25+26+27)
5544 = 11*12*13*14*15/(11+12+13+14+15)

Crossrefs

Cf. A370601

Sequence in context: A314563 A314564 A314565 * A365316 A001082 A242090

Adjacent sequences: A126692 A126693 A126694 * A126696 A126697 A126698

Keyword

easy,nonn

Author

Paolo P. Lava and Giorgio Balzarotti, Feb 15 2007, corrected Feb 20 2007 and Mar 06 2007

Status

approved