A332055 Tower of 8's modulo n.

0, 0, 1, 0, 1, 4, 1, 0, 1, 6, 3, 4, 1, 8, 1, 0, 1, 10, 11, 16, 1, 14, 6, 16, 6, 14, 19, 8, 20, 16, 8, 0, 25, 18, 1, 28, 26, 30, 1, 16, 10, 22, 35, 36, 1, 6, 25, 16, 8, 6, 1, 40, 28, 46, 36, 8, 49, 20, 4, 16, 34, 8, 1, 0, 1, 58, 24, 52, 52, 36, 8, 64, 8, 26, 31

Offset: 1

Author

Jinyuan Wang, Mar 04 2020

Keywords

• nonn

Comments

a(n) = (8^(8^(8^(8^ ... )))) mod n, provided sufficient 8's are in the tower such that adding more doesn't affect the value of a(n).

Crossrefs

Cf. A240162, A245970, A245971, A245972, A245973, A245974, A246496, A332054.

Programs

PARI

a(n) = {my(b, c=0, d=n, k=1, x=1); while(k==1, z=x; y=1; b=1; while(z>0, while(y
				

Formula

a(n) = 8^(A000010(n) + a(A000010(n))) mod n.

a(n) = (8^^k) mod n, if n < A246496(k), where ^^ is Knuth's double-arrow notation.