A115157 Numbers abc such that (a+2)(b+2)(c+2)=2abc.

480, 504, 560, 576, 630, 672, 720, 792, 840, 960, 1320, 1350, 1440, 1512, 1530, 1680, 1950, 2450, 2520, 4290

Offset

1,1

Comments

There are 20 rectangular parallelepipeds with integer edges such that increasing each edge by 2 doubles the volume, sorted in increasing volume: {6,8,10}, {6,7,12}, {5,8,14}, {6,6,16}, {5,7,18}, {4,12,14}, {4,10,18}, {4,9,22}, {5,6,28}, {4,8,30}, {3,20,22}, {3,18,25}, {3,16,30}, {4,7,54}, {3,15,34}, {3,14,40}, {3,13,50}, {5,5,98}, {3,12,70}, {3,11,130}

Links

Table of n, a(n) for n=1..20.

Example

The third smallest product of abc such that (a+2)(b+2)(c+2)=2abc is 560, so a(3)=560.

Crossrefs

Sequence in context: A025025 A108256 A262222 * A019287 A258551 A257415

Adjacent sequences: A115154 A115155 A115156 * A115158 A115159 A115160

Keyword

fini,full,nonn

Author

Graeme McRae, Jan 14 2006

Status

approved