A097582 Base 7 representation of the concatenation of the first n numbers with the most significant digits first.

1, 15, 234, 3412, 50664, 1022634, 13331215, 206636142, 3026236221, 614636352655, 155123512633260, 35001313215554565, 10403265603212022112, 2132066345452131466644, 434014101450663623262042

Offset

1,2

Comments

Consider numbers of the form 1, 12, 123, 1234, ..., N. Find the highest power of 7^p such that 7^p < N. Then p = [log(N)/log(7)] and for 0 <= qi <= 6 [N/7^p] = q1 + r1 [r1/7^(p-1)] = q2 + r2 ........................ rp/7^1 = qp + rp+1 rp+1/7^0 = qp+1 0 For N = 1234, p = [log(1234)/log(7)] = 3 division quot rem 1234/7^3 = 3 205 205/7^2 = 4 9 9/7^1 = 1 2 2/7^0 = 2 0 The sequence of quotients, top down, forms the entry in the table for 1234. Obviously this algorithm works for any N.

Links

Seiichi Manyama, Table of n, a(n) for n = 1..318

Formula

a(n) = A007093(A007908(n)). - Seiichi Manyama, Apr 23 2022

Crossrefs

Cf. A007908, A050926, A097580, A097583.

Cf. A007093.

Sequence in context: A097185 A372195 A178299 * A351527 A057007 A209118

Adjacent sequences: A097579 A097580 A097581 * A097583 A097584 A097585

Keyword

base,nonn

Author

Cino Hilliard, Aug 29 2004

Status

approved