A174163 a(n) = (A173919(k)*A173919(k+1))/2.

1, 3, 6, 10, 15, 21, 35, 55, 66, 78, 104, 136, 153, 171, 209, 253, 322, 406, 435, 465, 558, 666, 740, 820, 861, 903, 989, 1081, 1222, 1378, 1537, 1711, 1770, 1830, 2013, 2211, 2345, 2485, 2556, 2628, 2847, 3081, 3239, 3403, 3652, 3916, 4272, 4656, 4850, 5050, 5151, 5253

Offset: 1

Author

Giovanni Teofilatto, Mar 10 2010

Keywords

• nonn

Comments

Triangular numbers are (n*(n+1))/2 with n or n+1 twin prime

a(n)+a(n+1) is square: 1,4,9,16,25,36,121,144,289,324...

Crossrefs

Cf. A173919

Extensions

Corrected definition and insert a comment Giovanni Teofilatto, Apr 13 2010

Corrected definition and extended Giovanni Teofilatto, Apr 14 2010

Missing numbers (35, 104 etc.) inserted by R. J. Mathar, Aug 23 2010