A277850 a(n+1) = floor(log(a(n))+1) if this number does not occur earlier, a(n+1) = a(n)^2 else; a(n) = n for n <= 2.

0, 1, 2, 4, 16, 3, 9, 81, 5, 25, 625, 7, 49, 2401, 8, 64, 4096, 16777216, 17, 289, 6, 36, 1296, 1679616, 15, 225, 50625, 11, 121, 14641, 10, 100, 10000, 100000000, 19, 361, 130321, 12, 144, 20736, 429981696, 20, 400, 160000, 25600000000, 24, 576, 331776, 13, 169, 28561, 815730721, 21, 441, 194481, 37822859361, 1430568690241985328321

Offset

0,3

Comments

A variant of A217727. Appears to be a permutation of the integers.

Links

Table of n, a(n) for n=0..56.

Prog

(PARI) {print1("0, 1, "a=2); u=[]; for(i=2, 99, u=setunion(u, [a]); while(#u>1&&u[2]==u[1]+1, u=u[^1]); my(t=log(a)\1+1); print1(", "a=if(t>u[1]&&!setsearch(u, t), t, a^2))}

Crossrefs

Cf. A217727.

Sequence in context: A153064 A125594 A097542 * A332352 A217291 A364247

Adjacent sequences: A277847 A277848 A277849 * A277851 A277852 A277853

Keyword

nonn

Author

M. F. Hasler, Nov 20 2016

Status

approved