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 A283626 #12 Mar 14 2017 00:34:17 %S A283626 1,4,7,13,13,25,19,38,37,49,31,74,37,73,79,104,49,125,55,143,121,121, %T A283626 67,203,121,145,171,221,85,263,91,272,205,193,199,354,109,217,247,383, %U A283626 121,398,127,377,381,265,139,531,253,443,331,455,157,558,355,587,373 %N A283626 Number of integer triples (x,y,z), x > 0, y > 0, z > 0, such that x <= p, y <= q, z <= r for any factorization n = p*q*r. %C A283626 This sequence is a three-dimensional equivalent of A138808. %C A283626 a(n) >= 3*n-2, with equality iff n is not composite. %C A283626 a(n) >= 3*A138808(n)-3*n+1, with equality iff n has at most 2 prime factors (counted with multiplicity). %H A283626 Rémy Sigrist, <a href="/A283626/b283626.txt">Table of n, a(n) for n = 1..1000</a> %H A283626 Rémy Sigrist, <a href="/A283626/a283626.png">Illustration of the first terms</a> %o A283626 (PARI) a(n)=my(h=matrix(n,n)); fordiv(n,d, fordiv(n/d,dd, for(x=1,d, for(y=1,dd,h[x,y]=max(h[x,y],n/d/dd))))); return(sum(x=1,n, sum(y=1,n,h[x,y]))) %Y A283626 Cf. A138808. %K A283626 nonn %O A283626 1,2 %A A283626 _Rémy Sigrist_, Mar 12 2017