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A098129 Concatenate 1 once, 2 twice, 3 three times, up to n n times. 6
1, 122, 122333, 1223334444, 122333444455555, 122333444455555666666, 1223334444555556666667777777, 122333444455555666666777777788888888, 122333444455555666666777777788888888999999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..31

FORMULA

a(n+1) = a(n)*floor(log_10(A000461(n+1)) + 1) + A000461(n+1). - Paolo P. Lava, Mar 15 2010

EXAMPLE

a(4) = 1223334444 because 1 concatenated once then concatenated with 2 twice and 3 three times and 4 four times gives 1223334444.

MAPLE

P:=proc(i) local a, j, n; a:=0; for n from 1 by 1 to i do j:=n*(10^(n*floor(log10(10*n)))-1)/(10^floor(log10(10*n))-1); a:=a*10^floor(log10(j)+1)+j; print(a); od; end: P(12); # Paolo P. Lava, Mar 15 2010

# second Maple program:

a:= n-> parse(cat(seq(i$i, i=1..n))):

seq(a(n), n=1..12);  # Alois P. Heinz, Mar 07 2018

CROSSREFS

Cf. A000461.

Sequence in context: A208390 A282274 A208397 * A198603 A237640 A258489

Adjacent sequences:  A098126 A098127 A098128 * A098130 A098131 A098132

KEYWORD

easy,nonn,base

AUTHOR

Michael Joseph Halm, Jan 04 2005

EXTENSIONS

Offset and a(8) corrected by Seiichi Manyama, Mar 07 2018

STATUS

approved

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Last modified January 21 16:03 EST 2022. Contains 350479 sequences. (Running on oeis4.)