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A334620 a(n) is the smallest multiple of n formed by the concatenation 1,2,3,...,k for some k. 1
1, 12, 12, 12, 12345, 12, 1234567891011, 123456, 12345678, 12345678910, 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..144

FORMULA

a(n) is the smallest multiple of n appearing in A007908.

EXAMPLE

a(3) = 12, because 12 is the smallest multiple of 3 that appears in A007908.

MAPLE

f:= proc(n) local x, i;

x:= 0;

for i from 1 do

  x:= x*10^(1+ilog10(i))+i;

  if x mod n = 0 then return x fi

od

end proc:

map(f, [$1..20]); # Robert Israel, Oct 25 2020

MATHEMATICA

smn[n_]:=Module[{k=1, c=1}, While[!Divisible[c, n], k++; c= c*10^IntegerLength[ k]+ k]; c]; Array[ smn, 20] (* Harvey P. Dale, Apr 04 2022 *)

PROG

(PARI) a(n) = j=""; for(k=1, oo, j=eval(concat(Str(j), k)); if(j%n==0, return(j)))

CROSSREFS

Cf. A007908, A075002.

Sequence in context: A134324 A268914 A056627 * A061074 A064161 A260528

Adjacent sequences:  A334617 A334618 A334619 * A334621 A334622 A334623

KEYWORD

nonn,base,easy

AUTHOR

Eder Vanzei, Sep 09 2020

STATUS

approved

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Last modified May 25 02:55 EDT 2022. Contains 354047 sequences. (Running on oeis4.)