

A241811


a(1) = 1, a(2) = 0; for n >= 3, a(n) = least number not included earlier that divides the concatenation of all previous terms.


5



1, 0, 2, 3, 11, 71, 29, 9, 683, 67, 7, 743, 739, 1933, 23, 161, 21, 37, 19, 17, 119, 49, 332534262883, 13, 39, 13739483941387, 83, 111, 79853560395691, 5431567, 70610371, 69, 51, 4112497, 28384496881337963, 353, 77, 1531, 42787, 63, 27, 41, 709, 33, 81, 487, 139697
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OFFSET

1,3


LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..68


EXAMPLE

a(1)=1 and a(2)=0. a(1) U a(2) = 10 and its divisors are 1, 2, 5, 10. Therefore 2 is the least number not yet present in the sequence which divides 10. Again, a(1) U a(2) U a(3) = 102 and its divisors are 1, 2, 3, 6, 17, 34, 51, 102. Therefore a(4)=3, etc.


MAPLE

with(numtheory):
T:=proc(t) local x, y; x:=t; y:=0; while x>0 do x:=trunc(x/10); y:=y+1; od; end:
P:=proc(q) local a, b, c, k, n; b:=10; print(1); print(0); c:=[0, 1];
for n from 1 to q do a:=sort([op(divisors(b))]); for k from 2 to nops(a) do
if not member(a[k], c) then c:=[op(c), a[k]]; b:=a[k]+b*10^T(a[k]); print(a[k]); break;
fi; od; od; end: P(30);


CROSSREFS

Cf. A096097, A096098, A240588.
Sequence in context: A001052 A184310 A301347 * A155187 A109132 A279084
Adjacent sequences: A241808 A241809 A241810 * A241812 A241813 A241814


KEYWORD

nonn,base


AUTHOR

Paolo P. Lava, Apr 29 2014


EXTENSIONS

a(23)a(28) from Zak Seidov, May 08 2014
a(29)a(47) from Giovanni Resta, Aug 15 2019


STATUS

approved



