A185257 Side of triangle of the sum of pairs of triangular numbers whose sum and difference are triangular.

8, 23, 46, 59, 108, 106, 156, 182, 346, 348, 542, 766, 727, 717, 1071, 1153, 977, 1640, 1739, 1703, 2019, 1841, 1834, 2628, 2668, 2804, 2278, 2679, 2817, 2918, 4105, 4243, 4921, 4028, 5936, 5528, 4728, 7302, 8576, 7453, 7184, 9516, 9630, 11107, 11828, 11889, 12241

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) = 23, 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, A185258.

Sequence in context: A226600 A178072 A351966 * A033951 A209992 A212118

Adjacent sequences: A185254 A185255 A185256 * A185258 A185259 A185260

Keyword

nonn

Author

Martin Renner, Jan 20 2012

Status

approved