A185258 - OEIS

%I #7 Mar 31 2012 10:24:16

%S 3,11,25,20,56,73,51,42,49,183,117,406,532,602,356,325,842,144,164,

%T 900,119,1406,1630,1011,1156,935,2050,2000,2222,2541,1690,2488,1981,

%U 3699,1308,2924,4371,897,311,5113,5735,3783,5549,1807,696,5654,6478

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

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

%e 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.

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

%K nonn

%O 1,1

%A _Martin Renner_, Jan 20 2012