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 A179273 #8 Aug 11 2014 22:45:44 %S A179273 2,5,7,11,19,23,29,41,47,71,79,89,109,131,167,181,223,239,271,359,379, %T A179273 419,439,461,599,701,727,811,839,929,991,1087,1223,1259,1367,1481, %U A179273 1559,1721,1847,1979,2069,2161,2207,2351,2399,2549,2861,2969,3023,3079,3191 %N A179273 Primes in A179272. %C A179273 Primes of form floor(((n^2)/4) - (n/2) - 1). Primes in sharp upper bound on Rosgen overlap number n-vertex graph with n => 14, formula abused here for nonnegative integers. There seem to be more primes (29) through n = 60 of floor(((n^2)/4) - (n/2) - 1) than one might expect. What fraction through n = 1000 are prime? %H A179273 Harvey P. Dale, <a href="/A179273/b179273.txt">Table of n, a(n) for n = 1..1000</a> %H A179273 Daniel W. Cranston, Nitish Korula, Timothy D. LeSaulnier, Kevin Milans, Christopher Stocker, Jennifer Vandenbussche, Douglas B. West, <a href="http://arxiv.org/abs/1007.0804">Overlap Number of Graphs</a>, Jul 06, 2010. %e A179273 a(1) = floor(((5^2)/4) - (5/2) - 1) = floor(16/4 - 5/2 - 1) = floor(11/4) = 2. %e A179273 a(2) = floor(((6^2)/4) - (6/2) - 1) = floor(36/4 - 6/2 - 1) = floor(5) = 5. %t A179273 Select[Table[Floor[n^2/4-n/2-1],{n,5,200}],PrimeQ] (* _Harvey P. Dale_, Oct 12 2012 *) %Y A179273 Cf. A000040, A179272. %K A179273 easy,nonn %O A179273 1,1 %A A179273 _Jonathan Vos Post_, Jul 07 2010 %E A179273 More terms from _R. J. Mathar_, Oct 15 2010