31590

Appears in sequences

• a(n) = (n^3 + n)*3^n.at n=4A121607
• Riordan array ((1-x)/(1-3*x), x*(1-x)/(1-3*x)).at n=47A125693
• Subset of A020342 (vampire numbers, definition 1) listing numbers which have more than one such representation of the desired form.at n=13A144563
• a(n+1) = a(n) + floor(a(n)/4) with a(0)=4.at n=42A182305
• Number of numbers whose base 5/4 expansion (see A024634) has n digits.at n=42A245357
• G.f. A(x) satisfies A(x) = (1 + 9*x*A(x)^2)^(1/3).at n=9A376636
• Numbers k such that sigma(k) = psi(k) + phi(k) + tau(k)^2.at n=15A390421