

A097582


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


0



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

1,2


LINKS

Table of n, a(n) for n=1..15.


FORMULA

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^(p1)] = 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.


CROSSREFS

Sequence in context: A231411 A097185 A178299 * A057007 A209118 A093745
Adjacent sequences: A097579 A097580 A097581 * A097583 A097584 A097585


KEYWORD

base,nonn


AUTHOR

Cino Hilliard, Aug 29 2004


STATUS

approved



