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 A153078 #21 Sep 10 2019 22:21:31 %S A153078 0,1,1,2,2,5,2,4,5,3,7,5,10,2,8,4,5,6,11,32,42,68,24,87 %N A153078 Number of values of m such that sigma(m) = A002110(n) where A002110(n) is the product of the first n primes. %H A153078 Max A. Alekseyev, <a href="https://www.emis.de/journals/JIS/VOL19/Alekseyev/alek5.html">Computing the Inverses, their Power Sums, and Extrema for Euler's Totient and Other Multiplicative Functions</a>. Journal of Integer Sequences, Vol. 19 (2016), Article 16.5.2. %F A153078 a(n) = A054973(A002110(n)). - _Ray Chandler_, Dec 28 2008 %e A153078 a(10) = 3 because 2388809736, 3450503048 and 3696967556 are the only numbers with a sigma value = A002110(10). A002110(10) = 6469693230 = 2*3*5*7*11*13*17*19*23*29. %Y A153078 Cf. A000203, A002110, A153076, A153077. %K A153078 nonn,more %O A153078 1,4 %A A153078 _Donovan Johnson_, Dec 19 2008 %E A153078 a(12)-a(21) from _Ray Chandler_, Dec 28 2008 %E A153078 a(22)-a(24) from _Max Alekseyev_, Jan 27 2012