OFFSET
1,1
COMMENTS
x = (10^21 - 7)/69 = 14492753623188405797.
a(1) = 7*x*10 + 7, a(2) = 8*x*10 + 8, a(3) = 9*x*10 + 9.
LINKS
Robert Israel, Table of n, a(n) for n = 1..135
Wikipedia, Parasitic number.
FORMULA
From Robert Israel, Aug 22 2017: (Start)
a(3k-2) = 7(10^(22k)-1)/69.
a(3k-1) = 8(10^(22k)-1)/69.
a(3k) = 9(10^(22k)-1)/69.
a(n+6) = (10^22+1) a(n+3) - 10^22 a(n).
G.f.: (1304347826086956521739*x^2 + 1159420289855072463768*x + 1014492753623188405797)/
(10^22*x^6 - (10^22+1)*x^3 + 1). (End)
EXAMPLE
b = 101449275362318840579.
a(1) = b*10 + 7,
7*a(1) = 7101449275362318840579 = 7*10^21 + b.
MAPLE
seq(seq(y*((10^(22*k)-1)/69), y=7..9), k=1..6); # Robert Israel, Aug 22 2017
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Seiichi Manyama, Aug 21 2017
STATUS
approved