OFFSET
1,3
FORMULA
a(n) = Sum_{k=1..floor((n+1)/2)} A023531(n+1-k). - Sean A. Irvine, Jun 11 2019
MATHEMATICA
Array[Sum[k Boole@ IntegerQ@ Sqrt[8 # + 9] &[# + 1 - k], {k, Floor[(# + 1)/2]}] &, 82] (* Michael De Vlieger, Jun 12 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Missing a(21)=10 inserted and title simplified by Sean A. Irvine, Jun 11 2019
STATUS
approved