A358992 a(n) is the number of digits in the product of the first n odd numbers not divisible by 5.

1, 1, 1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 15, 16, 18, 19, 21, 22, 24, 26, 28, 29, 31, 33, 35, 36, 38, 40, 42, 44, 46, 48, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 82, 84, 86, 88, 90, 92, 94, 96, 99, 101, 103, 105, 107, 109, 112, 114, 116

Offset: 0

Author

Stefano Spezia, Dec 09 2022

Keywords

• nonn
• base

Crossrefs

Cf. A045572, A055642, A356860, A358990.

Cf. A358991 (number of zero digits), A358993 (number of nonzero digits).

Programs

Mathematica

Table[Length[IntegerDigits[Product[2i+2Floor[(i-3)/4]+1, {i, n}]]], {n, 0, 65}]

Formula

a(n) = A055642(A358990(n)).