OFFSET
1,5
MATHEMATICA
Select[RecurrenceTable[{a[0]==0, a[1]==1, a[n]==Abs[a[n-1]+2a[n-2]-n]}, a, {n, 200}], EvenQ]/2 (* Harvey P. Dale, Oct 24 2018 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
EXTENSIONS
Zero prepended by Harvey P. Dale, Oct 24 2018
STATUS
approved