

A185258


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


7



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
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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) = 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



