A336256 The cardinalities of the sets A(n), where A(0) is the empty set and A(n+1) is the union of A(n) and the Collatz orbit of the smallest natural number missing in A(n).

0, 1, 4, 9, 10, 20, 23, 24, 33, 34, 39, 42, 43, 46, 141, 142, 145, 146, 149, 161, 162, 170, 173, 174, 179, 180, 187, 190, 191, 204, 205, 208, 209, 212, 220, 221, 230, 231, 232, 239, 240, 243, 244, 247, 252, 253, 256, 257, 260, 261, 262, 267, 270, 271, 284, 285

Offset

0,3

Links

Table of n, a(n) for n=0..55.

Prog

(PARI) firstMiss(A) = { my(i); if(#A == 0 || A[1] > 0, return(0)); for(i = 1, A[#A] + 1, if(!setsearch(A, i), return(i))); };
iter(A) = { my(a = firstMiss(A)); while(!setsearch(A, a), A = setunion(A, Set([a])); a = if(a % 2, 3*a+1, a/2)); A; };
makeVec(m) = { my(v = [], A = Set([]), i); for(i = 1, m, v = concat(v, #A); if (i < m, A = iter(A))); v; };
makeVec(56)

Crossrefs

Cf. A061641, A336938.

Sequence in context: A356417 A004631 A316113 * A245096 A352097 A354853

Adjacent sequences: A336253 A336254 A336255 * A336257 A336258 A336259

Keyword

nonn

Author

Markus Sigg, Aug 08 2020

Status

approved