OFFSET
0,1
COMMENTS
Let a,b be integers defined in A018247, A018248 satisfying a^2=a, b^2=b, obviously a^3=a, b^3=b; let c,d,e,f be integers defined in A091661, A063006, A091663, A091664; then c^3=c, d^3=d, e^3=e, f^3=f, c+d=1, a+e=1, b+f=1, b+c=a, d+f=e, a+f=c, a=f+1, b=e+1, cd=-1, af=-1, gh=-1 where -1=.....999999999.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..9999 (terms 0..999 from Paul D. Hanna)
FORMULA
x = r^2 where r = ...1441224165530407839804103263499879186432 (A120817). x = 10-adic lim_{n->oo} 4^(5^n). - Paul D. Hanna, Jul 06 2006
EXAMPLE
x equals the limit of the (n+1) trailing digits of 4^(5^n):
4^(5^0) = (4), 4^(5^1) = 10(24), 4^(5^2) = 1125899906842(624), ...
x = ...0557423423230896109004106619977392256259918212890624.
MATHEMATICA
To calculate c, d, e, f use Mathematica algorithms for a, b and equations: c=a-b, d=1-c, e=b-1, f=a-1.
PROG
(PARI) {a(n)=local(b=4, v=[]); for(k=1, n+1, b=b^5%10^k; v=concat(v, (10*b\10^k))); v[n+1]} \\ Paul D. Hanna, Jul 06 2006
(PARI) (A091664_vec(n)=Vecrev(digits(lift(chinese(Mod(0, 2^n), Mod(-1, 5^n))))))(99) \\ M. F. Hasler, Jan 26 2020
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Edoardo Gueglio (egueglio(AT)yahoo.it), Jan 28 2004
STATUS
approved