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A123872 Start with the seed a(0)=2. The minimum number, different from 1, that multiplied by 2 (seed) produces a number with 2 as its rightmost digit is a(1)=6. Then 6*2=12. Again, the minimum number that multiplied by 12 produces 12 as its rightmost digits is a(2)=26 (12*26=312). And so on. 3
2, 6, 26, 126, 6251, 62500001 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

REFERENCES

G. Balzarotti and P. P. Lava, Le sequenze di numeri interi, Hoepli, 2008, p. 99.

LINKS

Table of n, a(n) for n=0..5.

EXAMPLE

a(0)=2;

a(1)=6 because 2*6 = 12;

a(2)=26 because 12*26 = 312;

a(3)=126 because 312*126 = 39312;

a(4)=6251 because 39312*6251 = 245739312;

a(5)=62500001 because 245739312*62500001 = 15358707245739312.

MAPLE

P:=proc(q, h) local a, b, k, n; a:=h; b:=ilog10(a)+1; print(h);

for k from 1 to 10 do for n from 2 to q do

if ((a*n) mod 10^b)=a then print(n); a:=a*n; b:=ilog10(a)+1;

break; fi; od; od; end: P(10^9, 2);

CROSSREFS

Cf. A123873-A123875.

Sequence in context: A192808 A034474 A306041 * A230071 A030937 A030827

Adjacent sequences:  A123869 A123870 A123871 * A123873 A123874 A123875

KEYWORD

nonn,base,more

AUTHOR

Paolo P. Lava and Giorgio Balzarotti, Oct 16 2006

STATUS

approved

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Last modified August 20 22:45 EDT 2019. Contains 326155 sequences. (Running on oeis4.)