108241

Appears in sequences

• a(n) = (10*n + 9)^2.at n=32A017378
• a(n) = (11*n + 10)^2.at n=29A017510
• a(n) = (12*n + 5)^2.at n=27A017582
• Composite numbers whose prime factors contain no digits other than 4 and 7.at n=12A036318
• a(n) = (Lucas(8*n) - 2)/45.at n=4A049682
• Numbers n such that n*phi(n-1) is a perfect square.at n=34A069069
• Expansion of g.f. -(1+27*x^2)/((1+3*x)*(1-2*x+9*x^2)).at n=11A106632
• Squares of the form 3S + 4, where S is a semiprime.at n=32A112630
• Squares of the form 4*A014574(n-1) + 1.at n=22A131706
• Indices k of perfect squares among 17-gonal numbers A051869(k) = k*(15*k - 13)/2.at n=4A137880
• Squares that becomes a prime number when prefixed with a 9.at n=18A167724
• The greedy sequence of real numbers at least 1 that do not contain any 3-term geometric progressions with integer ratio.at n=50A235054
• Perfect squares of the form prime(k+1)^2 - prime(k)^2 + 1 where prime(k) is the k-th prime number.at n=40A289829
• Squares of composite numbers k that are abelian orders.at n=22A350345
• a(n) is the smallest integer k > n such that sqrt(1/n + 1/k) is a rational number; or 0 if no such k exists.at n=46A379815