18633

Appears in sequences

• Numbers k such that phi(k) is equal to A008473(k-1).at n=5A039780
• Smaller terms in the pairs of numbers (a < b) in the sequence {a,b}-> {Max[{a,b}]-Min[{a,b}],k*Min[{a,b}]} with k=3 and the first pair {a=1,b=2}. See A075256.at n=51A075257
• a(n) = 16*n^2 + 4*n + 1.at n=34A082041
• p^2-p+1 central polygonal numbers with prime indices A002061(prime(n)).at n=32A119959
• Triangle T(n,k), read by rows, defined by T(n,k)=3*T(n-1,k)-T(n-1,k-1)-T(n-2,k), T(0,0)=1, T(1,0)=2, T(1,1)=-1, T(n,k)=0 if k<0 or if k>n.at n=49A123971
• Indices m such that A128646(m)-1 is prime, where A128646 = denominator of partial sums of 1/(p(i)-1).at n=57A137689
• Number of (w,x,y) with all terms in {0,...,n} and w<x+y and x<y.at n=35A212980
• Numbers n such that Q(sqrt(n)) has class number 9.at n=30A218041
• Fundamental discriminants of real quadratic number fields with class number 9.at n=20A218159
• G.f.: 1/((1-t^11)^2*(1-t)*(1-t^3)*(1-t^5)*(1-t^7)*(1-t^9)*(1-t^13)*(1-t^15)*(1-t^17)*(1-t^19)*(1-t^21)).at n=65A266751
• G.f. satisfies: A(x) = Sum_{n>=0} x^n * (1 + x*A(x)^(n+1))^n.at n=9A300042
• Intersection of A002061 and A016105.at n=31A370519