A358991 a(n) is the number of zero digits in the product of the first n odd numbers not divisible by 5.

0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 2, 1, 0, 2, 1, 1, 2, 2, 3, 2, 2, 2, 3, 2, 4, 5, 2, 4, 1, 3, 4, 5, 6, 9, 5, 4, 6, 4, 7, 7, 10, 5, 7, 10, 8, 9, 8, 4, 7, 4, 15, 9, 4, 7, 12, 9, 8, 14, 12, 5, 14, 12, 6, 11, 10, 14, 17, 17, 11, 19, 11, 15, 19, 15, 13, 14, 11, 19

Offset: 0

Author

Stefano Spezia, Dec 09 2022

Keywords

• nonn
• base

Crossrefs

Cf. A045572, A055641, A356859, A358990.

Cf. A358992 (number of digits), A358993 (number of nonzero digits).

Programs

Mathematica

Table[Count[IntegerDigits[Product[2i+2Floor[(i-3)/4]+1, {i, n}]], 0], {n, 0, 80}]

Formula

a(n) = A055641(A356990(n)).