A245404 Number of nonnegative integers with property that their base 7/2 expansion (see A024639) has n digits.

7, 21, 70, 245, 861, 3010, 10535, 36876, 129066, 451731, 1581055, 5533696, 19367936, 67787776, 237257216, 830400256, 2906400896, 10172403136, 35603410976, 124611938416, 436141784456, 1526496245596, 5342736859586, 18699579008551, 65448526529925, 229069842854741

Offset

0,1

Links

Table of n, a(n) for n=0..25.

Example

The numbers 7-27 are represented by 20, 21, 22, 23, 24, 25, 26, 40, 41, 42, 43, 44, 45, 46, 60, 61, 62, 63, 64, 65, 66 respectively in base 7/2. These are the only integers with two digits, and so a(2)=21.

Prog

(Sage)
A=[1]
for i in [1..60]:
    A.append(ceil((7-2)/2*sum(A)))
[7*x for x in A]

Crossrefs

Cf. A024639, A081848.

Sequence in context: A152766 A152671 A113859 * A215494 A146533 A208534

Adjacent sequences: A245401 A245402 A245403 * A245405 A245406 A245407

Keyword

nonn,base

Author

James Van Alstine, Jul 21 2014

Status

approved