A023859 a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2), and t = A023532.

1, 0, 1, 3, 5, 4, 7, 6, 9, 13, 18, 17, 23, 21, 27, 25, 32, 40, 49, 47, 56, 54, 64, 62, 73, 71, 82, 94, 107, 105, 119, 117, 132, 130, 145, 142, 158, 155, 172, 190, 209, 207, 227, 224, 244, 241, 262, 259, 281, 278, 301, 298, 322, 346, 371, 368, 394, 391, 418, 415, 443, 440, 469, 466

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Programs

Mathematica

Array[Sum[k Boole@ Not@ IntegerQ@ Sqrt[8 # + 9] &[# + 1 - k], {k, Floor[(# + 1)/2]}] &, 64] (* Michael De Vlieger, Jun 12 2019 *)

Extensions

Title simplified by Sean A. Irvine, Jun 12 2019