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A269306 a(n+1) is the smallest integer such that the difference between its digital sum and the digital sum of a(n) is n. 1
0, 1, 3, 6, 19, 69, 399, 1999, 9999, 99999, 1999999, 39999999, 699999999, 19999999999, 699999999999, 39999999999999, 1999999999999999, 99999999999999999, 9999999999999999999, 1999999999999999999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

The digital sums are the triangular numbers A000217. A similar idea is in A268605 (thanks to Michel Marcus for this comment).

LINKS

Table of n, a(n) for n=1..20.

EXAMPLE

a(8) = 1999 and 1 + 9 + 9 + 9 = 28; so a(9) = 9999 because 9 + 9 + 9 + 9 = 36 and 36 - 28 = 8.

PROG

(Python)

s = 0

for i in range(1, 100):

..alfa = ""

..k = i + s

..s = k

..while k > 9:

....alfa = alfa + "9"

....k = k - 9

..alfa = str(k)+alfa

..print alfa

(PARI) findnext(x, k) = {sx = sumdigits(x); y = 1; while (sumdigits(y) - sx != k, y++); y; }

lista(nn) = {print1(x = 0, ", "); for (k=1, nn, y = findnext(x, k); print1(y, ", "); x = y; ); }

CROSSREFS

Cf. A000217, A268605.

Sequence in context: A058818 A184937 A215817 * A326317 A306522 A290784

Adjacent sequences:  A269303 A269304 A269305 * A269307 A269308 A269309

KEYWORD

nonn,base

AUTHOR

Francesco Di Matteo, Feb 23 2016

STATUS

approved

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Last modified March 3 03:03 EST 2021. Contains 341756 sequences. (Running on oeis4.)