login
A305930
Number of digits '0' in 3^n (in base 10).
2
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 3, 2, 0, 0, 1, 0, 0, 0, 1, 2, 0, 2, 2, 0, 4, 2, 3, 2, 2, 2, 2, 2, 1, 2, 2, 2, 1, 2, 3, 1, 2, 1, 2, 7, 6, 2, 5, 2, 4, 2, 2, 2, 1, 2, 4, 4, 3, 0, 2, 4, 2, 1, 1, 4, 3, 5, 4, 5, 4, 5, 3, 3, 2, 6, 6, 5, 3, 4, 5, 3, 5, 5, 2, 6, 6, 2, 6, 4, 7
OFFSET
0,22
FORMULA
a(n) = A055641(A000244(n)).
a(A030700(n)) = 0; a(A305934(n)) = 1; a(A305931(n)) >= 1; a(A305933(n,k)) = n.
EXAMPLE
3^10 = 59049 is the smallest power of 3 having a digit 0, so a(10) = 1 is the first nonzero term.
MATHEMATICA
Table[ Count[ IntegerDigits[3^n], 0], {n, 0, 100} ]
DigitCount[3^Range[0, 110], 10, 0]
PROG
(PARI) apply( A305930(n)=#select(d->!d, digits(3^n)), [0..99])
(Haskell) a305930 = a055641 . a000244
CROSSREFS
Cf. A027870 (analog for 2^k), A030700 (indices of zeros).
Cf. A063555: index of first appearence of n in this sequence.
Cf. A305933: table with n in row a(n).
Sequence in context: A369932 A324881 A350734 * A206590 A206825 A336551
KEYWORD
nonn,base
AUTHOR
M. F. Hasler, Jun 22 2018
STATUS
approved