20745

Appears in sequences

• Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 32.at n=8A031710
• Coefficients in the series (1 + x - x^4 - x^6 - x^8 - x^9 - x^10 - x^12 - x^14 ...)/(1 - x^2 - x^3 - x^5 - x^7 - x^11 - x^13 ...).at n=28A058354
• Numbers n such that sigma(n - phi(n)) = phi(n + phi(n)).at n=2A074887
• Integer quotients pi(m*prime(m))/m.at n=8A084298
• Numbers k such that 2k+1, 4k+1, 6k+1 and 8k+1 are primes.at n=15A124409
• Numbers k such that 2*k+1, 4*k+1, 8*k+1 and 16*k+1 are primes.at n=20A124412
• a(n) = a(n-2) + a(n-3) + a(n-4) - a(n-6), with a(0) = a(2) = a(3) = 1, a(1) = 0 and a(4) = a(5) = 2.at n=32A143438
• a(n) = 81*n^2 + 9.at n=15A157888
• Norm of coefficients in the expansion of 1 / (1 - x - 2*I*x^2), where I^2=-1.at n=9A218135