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 A226953 #8 Jul 17 2013 07:17:59 %S A226953 1,2,9,14,15,18,20,22,46,94,118,166,214,231,248,286,308,310,334,344, %T A226953 350,351,358,366,372,392,399,405,406,430,454,483,490,494,516,518,522, %U A226953 526,532,536,568,595,598,632,638,644,654,663,666 %N A226953 Leap year numbers: numbers n such that tau(phi(n)) = phi(tau(n))^2, where tau(n) is the number of divisors of n and phi(n) the Euler totient function. %C A226953 Paraphrasing Doug Iannucci, n is called a "leap year number" if tau(phi(n)) = phi(tau(n))^2 (366 is a leap year number, hence the sequence name). The beast number is a leap year number. The only prime leap year number is 2. %H A226953 Vincenzo Librandi, <a href="/A226953/b226953.txt">Table of n, a(n) for n = 1..1000</a> %e A226953 phi(666)=216, tau(216)=16, tau(666)=12, phi(12)=4, 4^2=16, therefore 666 is in the sequence. %t A226953 Select[Range[1000], DivisorSigma[0, EulerPhi[#]] == EulerPhi[DivisorSigma[0, #]]^2 &] %Y A226953 Cf. A137815 (Doug Iannucci's "year numbers"). %K A226953 easy,nonn %O A226953 1,2 %A A226953 _Jean-François Alcover_, Jun 24 2013