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.

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

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 * A349518 A155187 A338613

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