A083510 Members of A000124 which are the arithmetic mean of two other members.

4, 22, 29, 37, 79, 106, 154, 172, 191, 211, 254, 326, 352, 379, 466, 529, 667, 704, 904, 947, 991, 1036, 1129, 1177, 1276, 1379, 1486, 1541, 1597, 1654, 1712, 1771, 1892, 1954, 2279, 2347, 2557, 2629, 2776, 2927, 3004, 3082, 3161, 3404, 3571, 3742, 3829

Offset

1,1

Links

Table of n, a(n) for n=1..47.

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

Cf. A000124.

Sequence in context: A204341 A036920 A036921 * A277586 A078647 A031108

Adjacent sequences: A083507 A083508 A083509 * A083511 A083512 A083513

Keyword

nonn

Author

Amarnath Murthy, May 05 2003

Extensions

Corrected and extended by David Wasserman, Nov 18 2004

Status

approved