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A122098 Smallest number, different from 1, which when multiplied by "n" produces a number with "n" as its rightmost digits. 1
11, 6, 11, 6, 3, 6, 11, 6, 11, 11, 101, 26, 101, 51, 21, 26, 101, 51, 101, 6, 101, 51, 101, 26, 5, 51, 101, 26, 101, 11, 101, 26, 101, 51, 21, 26, 101, 51, 101, 6, 101, 51, 101, 26, 21, 51, 101, 26, 101, 3, 101, 26, 101, 51, 21, 26, 101, 51, 101, 6, 101, 51, 101, 26, 21 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All prime numbers p > 5 must be multiplied by 1+10^k, where k is the number of digits of p. The result is p U p. - Paolo P. Lava, Apr 11 2008

REFERENCES

G. Balzarotti and P. P. Lava, Le sequenze di numeri interi, Hoepli, 2008, p. 100

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

a(8)=6 because 8*6 = 48 and 6 is the minimum number that multiplied by 8 gives a number ending in 8.

a(12)=26 because 12*26=312 and 26 is the minimum number that multiplied by 12 gives a number ending in 12.

MAPLE

P:=proc(n) local a, b, i, j; print(11); for i from 2 by 1 to n do b:=trunc(evalf(log10(i)))+1; for j from 2 by 1 to n do a:=i*j; if i=a-trunc(a/10^b)*10^b then print(j); break; fi; od; od; end: P(101); # Paolo P. Lava, Apr 11 2008

MATHEMATICA

snrd[n_]:=Module[{k=2}, While[Mod[k*n, 10^IntegerLength[n]]!=n, k++]; k]; Array[ snrd, 70] (* Harvey P. Dale, Apr 08 2019 *)

CROSSREFS

Sequence in context: A236175 A193813 A080501 * A115943 A122088 A304053

Adjacent sequences:  A122095 A122096 A122097 * A122099 A122100 A122101

KEYWORD

nonn,base

AUTHOR

Paolo P. Lava and Giorgio Balzarotti, Oct 18 2006

STATUS

approved

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Last modified February 20 12:34 EST 2020. Contains 332076 sequences. (Running on oeis4.)