3880897

Properties

Appears in sequences

• Number of not-necessarily-symmetric n X 2 crossword puzzle grids.at n=16A034182
• Values of k such that {s(1),...,s(k)} is a palindrome, where {s(1),s(2),...} is the fixed point of the substitutions 0->1 and 1->110.at n=32A098894
• Expansion of (1+4*x+x^2)/((1-x^2)*(1-2*x-x^2)); a Pellian-related sequence.at n=16A114696
• a(1)=1, a(2)=17; thereafter a(n) = 6*a(n-1)-a(n-2)+c, where c=-4 if n is odd, c=12 if n is even.at n=8A184327
• Simple continued fraction expansion of product {k >= 0} (1 - 2*(N - sqrt(N^2-1))^(4*k+3))/(1 - 2*(N - sqrt(N^2-1))^(4*k+1)) at N = 3.at n=17A221193
• Primes p where q = p + 4 is also prime and rad((p+1)(p+2)(p+3)) < pq, where rad(k) is the largest squarefree number dividing k.at n=34A268350
• Sum of the legs of the unique primitive Pythagorean triple (x,y,z) such that (x-y+z)/2 is A002315(n) and such that its long leg and its hypotenuse are consecutive natural numbers.at n=4A379508
• Prime numbersat n=275331