523776

Appears in sequences

• a(n) = 2^(n-1)*(2^n - (-1)^n).at n=10A003674
• 3-perfect (triply perfect, tri-perfect, triperfect or sous-double) numbers: numbers such that the sum of the divisors of n is 3n.at n=2A005820
• a(n) = 2^(n-1)*(2^n - 1), n >= 0.at n=10A006516
• Dual pairs of integrals arising from reflection coefficients.at n=20A007179
• Multiply-perfect numbers: n divides sigma(n).at n=9A007691
• a(n) = 4^n*(4^n - 1)/2.at n=5A026337
• Numbers k such that the set of prime divisors of k is equal to the set of prime divisors of sigma(k).at n=34A027598
• Number of reversible strings with n beads of 2 colors. If more than 1 bead, not palindromic.at n=19A032085
• Number of reversible strings with n beads of 4 colors. If more than 1 bead, not palindromic.at n=9A032087
• a(n) = (nextprime(4^n) - nextprime(2^n))/2.at n=10A037131
• Sum of every 4th entry of row n in Pascal's triangle, starting at "n choose 0".at n=21A038503
• Sum of every 4th entry of row n in Pascal's triangle, starting at "n choose 1".at n=21A038504
• Number of elements of GF(2^n) with trace 0 and subtrace 0.at n=21A038518
• Number of elements of GF(2^n) with trace 1 and subtrace 0.at n=21A038520
• Erroneous version of A005820.at n=2A039688
• 1 / min{1/n - 1/a - 1/b > 0}, where a and b are integers.at n=30A045470
• Multiply perfect numbers that are neither harmonic numbers nor arithmetic numbers.at n=1A046987
• Number of subsets of {2,...,n} such that the product of their elements is congruent to 0 (mod n+1).at n=19A064381
• Numbers n such that sigma(n) / n is prime.at n=6A065997
• Abundant numbers n such that n = sigma(k) - 2k, where k = sigma(n) - 2n.at n=4A069085