A367612 - OEIS

%I #16 Jan 09 2025 12:35:56

%S 11,12,22,23,24,33,34,35,36,44,45,46,47,48,55,56,57,58,59,60,61,66,67,

%T 68,69,70,71,72,73,77,78,79,80,81,82,83,84,85,88,89,90,91,92,93,94,95,

%U 96,97,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122

%N Numbers that are the comma-child of exactly one positive number.

%C This is the complement of A367611.

%C See A367338 for definition of comma-child.

%C May also be called numbers that have a positive comma-predecessor.

%H Eric Angelini, Michael S. Branicky, Giovanni Resta, N. J. A. Sloane, and David W. Wilson, The Comma Sequence: A Simple Sequence With Bizarre Properties, <a href="http://arxiv.org/abs/2401.14346">arXiv:2401.14346</a>, Fibonacci Quarterly 62:3 (2024), 215-232.

%H Eric Angelini, Michael S. Branicky, Giovanni Resta, N. J. A. Sloane, and David W. Wilson, <a href="/A121805/a121805_1.pdf">The Comma Sequence: A Simple Sequence With Bizarre Properties</a>, Local copy.

%H N. J. A. Sloane, <a href="https://www.youtube.com/watch?v=_EHAdf6izPI">Eric Angelini's Comma Sequence</a>, Experimental Math Seminar, Rutgers Univ., January 18, 2024, Youtube video; <a href="https://sites.math.rutgers.edu/~zeilberg/expmath/sloane2024.pdf">Slides</a>

%o (Python)

%o def ok(n): y = int(str(n)[0]); x = (n-y)%10; return n - y - 10*x > 0

%o print([k for k in range(1, 123) if ok(k)]) # _Michael S. Branicky_, Dec 15 2023

%Y Cf. A121805, A367611.

%K nonn,base

%O 1,1

%A _Michael S. Branicky_ and _N. J. A. Sloane_, Dec 15 2023