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.
%I A109622 #23 Jan 20 2025 09:02:24
%S A109622 1,1,4,7,15,23,38,53,77,101,136,171,219,267,330,393,473,553,652,751,
%T A109622 871,991,1134,1277,1445,1613,1808,2003,2227,2451,2706,2961,3249,3537,
%U A109622 3860,4183,4543,4903,5302,5701,6141,6581,7064,7547,8075,8603
%N A109622 Number of different isotemporal classes of diasters with n peripheral edges.
%C A109622 See A092481 for the definition of isotemporal classes.
%D A109622 Benjamin de Bivort, Isotemporal classes of diasters, beachballs and daisies, preprint, 2005.
%F A109622 a(n=2k) = 1 + (Sum_{i=1..(n/2)-1} n*i-i^2+n+1) + (1/2)*((n/2)^2+3*(n/2)+2). a(n=2k+1) = 1 + (Sum_{i=1..(n-1)/2} n*i-i^2+n+1). [Corrected by _Sean A. Irvine_ after private communication with Benjamin de Bivort, Feb 13 2012]
%F A109622 a(n) = A005993(n) - n. - _Enrique Pérez Herrero_, Apr 22 2012
%e A109622 A diaster is defined to be any graph with a central edge with vertices of degree j and k and j+k peripheral edges connected to the central edge each terminating in a vertex of degree 1. a(5)=23 refers to diasters with 5 peripheral edges. These can be uniquely arranged with 0, 1 or 2 peripheral edges on a particular side, yielding 1, 10 and 12 isotemporal classes respectively each.
%Y A109622 Cf. A092481, A005993.
%K A109622 nonn,easy
%O A109622 0,3
%A A109622 Benjamin de Bivort (bivort(AT)fas.harvard.edu), Aug 02 2005
%E A109622 More terms from _Sean A. Irvine_, Feb 12 2012