OFFSET
1,1
EXAMPLE
4 = (1+7)/2, 37 = (7 +67)/2. etc.
PROG
(PARI) V = vector(5000); for (i = 1, 5000, V[i] = 1 + binomial(i, 2)); count = 0; i = 1; while (count < 50, i++; found = 0; j = i - 1; k = i + 1; x = 2*V[i]; while (!found && j, if (V[j] + V[k] > x, j--, if (V[j] + V[k] < x, k++, found = 1))); if (found, count++; print1(V[i], ", "))); \\ David Wasserman, Nov 18 2004
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, May 05 2003
EXTENSIONS
Corrected and extended by David Wasserman, Nov 18 2004
STATUS
approved