OFFSET
1,3
COMMENTS
For unitary anti-divisors of n are intended all the anti-divisors of n which are coprime to n.
LINKS
Paolo P. Lava, Table of n, a(n) for n = 1..1000
FORMULA
Anti-divisors of 14 are 3, 4, 9. Anti-divisors coprime to 14 are 3 and 9 and therefore a(14) = 3 + 9 = 12.
MAPLE
P:=proc(q) local a, k, n, v; v:=[]; for n from 1 to q do a:=0;
for k from 2 to n-1 do if abs((n mod k)-k/2)<1 then if gcd(n, k)=1
then a:=a+k; fi; fi; od; v:=[op(v), a]; od; print(op(v)); end: P(69);
# corrected by Paolo P. Lava, Aug 17 2024
MATHEMATICA
antiDivisors[n_Integer] := Cases[Range[2, n - 1], _?(Abs[Mod[n, #] - #/2] < 1 &)]; a240979[n_Integer] := Total[Select[antiDivisors[n], CoprimeQ[#, n] &]]; a240979 /@ Range[120] (* Michael De Vlieger, Aug 17 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Aug 06 2014
STATUS
approved