A377082 a(0) = 1, a(1) = 3, a(2) = 13; for n >= 2, a(n+1) = 2*3^((a(n)-1)/4) - 1.

1, 3, 13, 53, 3188645

Offset

0,2

Comments

The next term is too large to include.

a(n) is the least positive integer that requires n steps to reach 1 under iteration of the sum of squares of digits function in base 3 (A006287).

a(n) is also the least positive integer that requires n steps to reach 1 under iteration of the map A375212.

Links

Table of n, a(n) for n=0..4.

N. Bradley Fox et al., Elated Numbers, arXiv:2409.09863 [math.NT], 2024.

G. Lapointe, On finding the smallest happy numbers of any heights, arXiv:1904.12032 [math.NT], 2019.

Crossrefs

Cf. A006287, A007013, A375212.

Sequence in context: A121240 A065839 A066611 * A180933 A048514 A037779

Adjacent sequences: A377079 A377080 A377081 * A377083 A377084 A377085

Keyword

nonn

Author

N. Bradley Fox, Nathan Fox, Helen Grundman, Rachel Lynn, Changningphaabi Namoijam, Mary Vanderschoot, Oct 15 2024

Status

approved