A259604 (A259542(n) + A259542(n+1)) / 2.

3, 6, 10, 15, 10, 6, 10, 15, 21, 28, 36, 45, 36, 28, 36, 45, 55, 36, 21, 28, 36, 45, 36, 28, 36, 45, 55, 66, 78, 91, 78, 66, 78, 91, 105, 78, 55, 66, 78, 91, 78, 66, 78, 91, 105, 120, 136, 153, 120, 78, 91, 105, 91, 78, 66, 78, 105, 120, 136, 153, 171, 153

Offset: 1

Author

Reinhard Zumkeller, Jun 30 2015

Keywords

• nonn

Comments

All terms are triangular numbers by definition of A259542.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A259542, A000217, A086517, A259602, A259603, A259605.

Programs

Haskell

a259604 n = a259604_list !! (n-1)
a259604_list = zipWith ((flip div 2 .) . (+))
                       a259542_list $ tail a259542_list