262142

Appears in sequences

• a(n) = 2^n - 2.at n=18A000918
• a(2*n) = 3*2^n - 2; a(2*n+1) = 2^(n+2) - 2.at n=33A027383
• Numbers n such that uphi(sigma(n)) = n, where the uphi is the unitary phi function A047994.at n=29A030164
• Number of palindromes of length n using exactly two different symbols.at n=34A056453
• Number of palindromes of length n using exactly two different symbols.at n=35A056453
• Numerator of the expected time to finish a random Tower of Hanoi problem with n disks using optimal moves.at n=17A060590
• Biased numbers: n such that all terms of the sequence f(n), f(f(n)), f(f(f(n))), ..., 1, where f(k) = floor(k/2), are odd.at n=32A066880
• a(0) = 1; a(n) = a(n-1)+1 if n is even, otherwise a(n) = 2*a(n-1).at n=33A075427
• Largest term in periodic part of continued fraction expansion of square root of -1+2^n or 0 if -1+2^n is square.at n=33A077625
• Expansion of (1-x+2x^2)/((1-x)*(1-2x)).at n=17A095121
• Values of k such that the total number of 1's in the binary expansions of the first k integers is a multiple of k.at n=30A095376
• Divisors of perfect numbers (A000396), sorted.at n=42A096360
• Let S(n)=Sigma(n)/2. Numbers n such that S(S(n))=n, 1/2-Sociable number of order 1 or 2.at n=25A113791
• Semiprime nearest to 2^n. (In case of a tie, choose the smaller).at n=18A117405
• a(0) = 1, a(n) = (-1)^n*(2-2^(n-1)) for n>0.at n=19A122959
• Row sums of triangle A134066.at n=16A134067
• a(n) = a(n-1) + 2a(n-2).at n=18A135440
• a(n) = 3*a(n-1) - 3*a(n-2) + 2*a(n-3), with a(0) = a(1) = -1 and a(2) = 3.at n=18A135446
• Triangle read by rows: row n lists the divisors of n-th perfect number A000396(n) that are multiples of n-th Mersenne prime A000668(n).at n=31A139247
• Twice Mersenne primes A000668(n).at n=5A139257