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A184989 Digits of n and of n-1 interleaved in decimal representation. 1
10, 21, 32, 43, 54, 65, 76, 87, 98, 190, 1110, 1121, 1132, 1143, 1154, 1165, 1176, 1187, 1198, 2109, 2210, 2221, 2232, 2243, 2254, 2265, 2276, 2287, 2298, 3209, 3310, 3321, 3332, 3343, 3354, 3365, 3376, 3387, 3398, 4309, 4410, 4421, 4432, 4443, 4454, 4465, 4476, 4487, 4498, 5409, 5510, 5521, 5532, 5543, 5554, 5565, 5576, 5587, 5598 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A055642(a(n)) <= 2*A055642(n), equality holds iff n <> 10^k;

A007953(a(n)) = 2*A007953(n) - 1 + 9*A122840(n);

1, 10, 2207, 7877, 9829, 2240353, 6682447, ... are the first numbers m such that a(m) is a multiple of m.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..9999

MATHEMATICA

Table[FromDigits[Riffle[IntegerDigits[n], IntegerDigits[n-1]]], {n, 60}] (* Harvey P. Dale, Aug 11 2015 *)

PROG

(Haskell)

a184989 n = read $ interleave (show n) (show (n - 1)) :: Integer where

   interleave []     ys = ys

   interleave (x:xs) ys = x : interleave ys xs

CROSSREFS

Sequence in context: A095778 A065438 A017509 * A072806 A189402 A051942

Adjacent sequences:  A184986 A184987 A184988 * A184990 A184991 A184992

KEYWORD

nonn,base,look

AUTHOR

Reinhard Zumkeller, Mar 29 2011

STATUS

approved

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Last modified July 15 14:53 EDT 2019. Contains 325031 sequences. (Running on oeis4.)