OFFSET
0,4
LINKS
Stefano Spezia, Table of n, a(n) for n = 0..10000
FORMULA
a(n) = Sum_{k=1..n} A007953(k*(n-k)). - Andrew Howroyd, Apr 08 2023
MATHEMATICA
T[i_, j_]:=Total[IntegerDigits[i*j]]; Table[Sum[T[n-j, j], {j, 0, n}], {n, 0, 56}]
PROG
(PARI) a(n) = sum(k=1, n, sumdigits(k*(n-k))) \\ Andrew Howroyd, Apr 08 2023
CROSSREFS
KEYWORD
AUTHOR
Stefano Spezia, Apr 08 2023
STATUS
approved