

A185257


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


7



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
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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: A139433 A226600 A178072 * A033951 A209992 A212118
Adjacent sequences: A185254 A185255 A185256 * A185258 A185259 A185260


KEYWORD

nonn


AUTHOR

Martin Renner, Jan 20 2012


STATUS

approved



