25479

Appears in sequences

• a(n+1)-+a(n)=prime, a(n+1)*a(n)=Average of twin prime pairs, a(1)=1,a(2)=4.at n=32A154493
• a(n) = index of second occurrence of A161926(n) in A114381.at n=13A161927
• Sums of pairs of betrothed (or quasi-amicable) numbers.at n=6A179612
• G.f.: Sum_{n>=0} x^n / Product_{k=n*(n-1)/2+1..n*(n+1)/2} (1 - k*x).at n=7A249637
• Numbers which can be written uniquely as x^4 + y*(2y+1) + z*(3z+1), where x,y,z are integers with x>=0.at n=31A334147
• For 1<=x<=n, 1<=y<=n, write gcd(x,y) = u*x+v*y with u,v minimal; a(n) = n^4*s, where s is the population variance of the values of |v|.at n=11A345690