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A075013 Smallest k such that the decimal concatenation of k and k+1 is divisible by n. 1
1, 1, 1, 1, 4, 1, 5, 5, 4, 9, 16, 1, 7, 5, 4, 19, 3, 13, 22, 19, 16, 27, 2, 19, 24, 7, 31, 5, 31, 19, 27, 19, 16, 3, 9, 31, 26, 41, 7, 19, 28, 37, 20, 27, 4, 51, 20, 19, 16, 49, 52, 35, 32, 31, 49, 5, 22, 31, 66, 19, 32, 27, 58, 19, 9, 49, 6, 35, 28, 9, 26, 67, 13, 63, 49, 79, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..77.

EXAMPLE

a(16) = 19 as 16 divides 1920.

MATHEMATICA

With[{cnct=Table[FromDigits[Flatten[IntegerDigits/@{n, n+1}]], {n, 100}]}, Table[ Position[cnct, _?(Divisible[#, k]&), 1, 1], {k, 100}]]//Flatten (* Harvey P. Dale, Apr 11 2020 *)

PROG

(PARI) for(n=1, 100, k=1:while((k*(10^floor(log(k+1)/log(10)+1))+k+1)%n>0, k=k+1):print1(k", "))

CROSSREFS

Cf. A075114, A075115, A075116, A075117.

Sequence in context: A105721 A099310 A021880 * A117379 A007309 A333341

Adjacent sequences:  A075010 A075011 A075012 * A075014 A075015 A075016

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Sep 01 2002

EXTENSIONS

Corrected and extended by Ralf Stephan, Mar 23 2003

STATUS

approved

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Last modified May 12 23:09 EDT 2021. Contains 343829 sequences. (Running on oeis4.)