A185258 - OEIS

A185258

Side of triangle of the difference of pairs of triangular numbers whose sum and difference are triangular.

3, 11, 25, 20, 56, 73, 51, 42, 49, 183, 117, 406, 532, 602, 356, 325, 842, 144, 164, 900, 119, 1406, 1630, 1011, 1156, 935, 2050, 2000, 2222, 2541, 1690, 2488, 1981, 3699, 1308, 2924, 4371, 897, 311, 5113, 5735, 3783, 5549, 1807, 696, 5654, 6478

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

REFERENCES

Albert H. Beiler, Recreations in the theory of numbers, New York, Dover, (2nd ed.) 1966, p. 197, nr. 8.

LINKS

Table of n, a(n) for n=1..47.

EXAMPLE

a(2) = 11, since the pair of triangular numbers 171 = 18*(18+1)/2 and 105 = 14*(14+1)/2 produce the sum 276 = 23*(23+1)/2 and the difference 66 = 11*(11+1)/2 which are both triangular numbers.

CROSSREFS

Cf. A000217, A185128, A185129, A185223, A185233, A185243, A185253, A185257.

Sequence in context: A141595 A112051 A231068 * A118436 A293413 A056106

Adjacent sequences: A185255 A185256 A185257 * A185259 A185260 A185261

KEYWORD

nonn

AUTHOR

Martin Renner, Jan 20 2012

STATUS

approved