A030350 a(n) = (# 1's)-(# 2's) in first n terms of A030341.

0, 1, 0, 0, 1, 2, 3, 2, 3, 3, 2, 3, 2, 1, 0, 0, 0, 1, 2, 2, 3, 2, 2, 3, 3, 4, 5, 6, 7, 8, 7, 8, 9, 9, 8, 9, 10, 9, 10, 9, 8, 9, 9, 9, 8, 9, 9, 8, 7, 7, 6, 6, 7, 6, 7, 8, 7, 6, 7, 6, 6, 5, 4, 5, 4, 3, 2, 1, 0, 0, 0, 0, 1, 2, 2, 2, 3, 2, 2, 2, 3, 3, 4, 4, 5, 6, 7, 7, 8, 7

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• look

Comments

For k >= 1, a(3^k * (k - 1/2) + 1/2) = 1 and a(3^k * (k - 1/2) + 3/2) = a(3^k * (k - 1/2) + 5/2) = 0. - Robert Israel, Jun 23 2024

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A030341.

Programs

Maple

R:= 0: t:= 0:
for i from 1 to 100 do
  L:= convert(i,base,3);
  for j from 1 to nops(L) do
    if L[j] = 1 then t:= t+1 elif L[j] = 2 then t:= t-1 fi;
    R:= R,t;
  od
od:
R; # Robert Israel, Jun 23 2024

Extensions

a(1) = 0 inserted by Robert Israel, Jun 23 2024