cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A076138 a(1)=1; a(n+1) is the smallest integer > a(n) such that C_2k(a(n+1))=C_2k(a(n)) for k large enough, where C_m(n) is the modified Collatz map iterated m times on n ( x->x/2 if x is even x->(3x+1)/2 if x is odd).

Original entry on oeis.org

1, 4, 5, 6, 11, 14, 15, 16, 18, 19, 20, 21, 24, 25, 26, 27, 33, 34, 35, 43, 44, 45, 46, 47, 56, 57, 58, 59, 60, 61, 62, 63, 64, 72, 74, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 96, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 113, 130, 131, 132, 133, 134, 135
Offset: 1

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Author

Benoit Cloitre, Oct 31 2002

Keywords

Comments

a(n) seems to be asymptotic to 2*n and a(n)=2*n for some n (5, 14, 43, 54, 72, 93, ...)
Positions of 1's in A006513. - Sean A. Irvine, Mar 21 2025

Crossrefs

Formula

a(n+1) = min (k>a(n) : A076057(k)=A076057(a(n))).

Extensions

Missing 16 and 18 inserted by Sean A. Irvine, Mar 21 2025
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