6291456

Appears in sequences

• Numbers that are not the sum of 4 nonzero squares.at n=40A000534
• a(n) = 6*4^n.at n=10A002023
• Generalized Euler phi function (for p=2).at n=23A003473
• Expansion of g.f. (1+x)/(1-2*x).at n=22A003945
• Numbers that have a unique partition into a sum of four nonnegative squares.at n=39A006431
• a(n) = 3*2^n.at n=21A007283
• Berstel sequence: a(n+1) = 2*a(n) - 4*a(n-1) + 4*a(n-2).at n=30A007420
• Row sums of the Lucas triangle A029635.at n=22A042950
• Smallest number x such that cototient(x) = 2^n.at n=22A058764
• A hierarchical sequence (S(W'2{3}*c) - see A059126).at n=15A059162
• For n >= 2, let N_n denote the set of all unipotent upper-triangular real n X n matrices A such that for every k=1,2,...,n-1 the minor of A with rows 1,2,...,k and columns n-k+1,...,n is nonzero. a(n) is the number of connected components of N_n.at n=20A060344
• Reciprocal of n terminates with an infinite repetition of digit 6. Multiples of 10 are omitted.at n=15A064565
• a(1)=2, a(n+1) = 2*a(n) - phi(a(n)) where phi is the Euler totient function A000010.at n=33A072944
• a(n) = n*2^(n-6).at n=18A078836
• a(n) = 2*2^n - (-2)^n.at n=21A081631
• Numbers m such that the largest prime power in the factorization of m equals phi(m).at n=19A081808
• a(n) = sum of (n-1)-th row terms of triangle A134059.at n=22A082505
• Expansion of g.f. (1 + 6*x + 5*x^2)/((1-2*x)*(1+2*x)).at n=21A084431
• Number of ground-state 3-ball juggling sequences of period n.at n=13A084509
• a(0) = 1, a(n) = spf(n)*a(n-spf(n)), where spf=A020639 (smallest prime factor).at n=45A086931