2097150

Appears in sequences

• a(n) = 2^n - 2.at n=21A000918
• a(n) = 2^(2*n+1) - 2.at n=10A002446
• Number of Barlow packings with group P63/mmc(S) that repeat after 4n layers.at n=21A011946
• a(n) = 2*a(n-1) if n odd else 2*a(n-1) + 6.at n=19A014131
• a(2*n) = 3*2^n - 2; a(2*n+1) = 2^(n+2) - 2.at n=39A027383
• Number of palindromes of length n using exactly two different symbols.at n=41A056453
• Number of palindromes of length n using exactly two different symbols.at n=40A056453
• Number of primitive (aperiodic) palindromes using a maximum of two different symbols.at n=40A056458
• Number of primitive (aperiodic) palindromes using exactly two different symbols.at n=40A056463
• Number of primitive (period n) periodic palindromes using a maximum of two different symbols.at n=40A056493
• Number of primitive (period n) periodic palindromes using exactly two different symbols.at n=40A056498
• 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=38A066880
• a(0) = 1; a(n) = a(n-1)+1 if n is even, otherwise a(n) = 2*a(n-1).at n=39A075427
• 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=39A077625
• Number of rational knots with n crossings and unknotting number = 1 (chiral pairs counted only once).at n=41A078477
• Number of ways of 3-coloring an annulus consisting of n zones joined like a pearl necklace.at n=20A092297
• Expansion of (1-x+2x^2)/((1-x)*(1-2x)).at n=20A095121
• a(n) = 2^n+(-1)^n-1.at n=21A099430
• A Horadam-Jacobsthal sequence.at n=20A101622
• Number of palindromes (in base 4) below 4^n.at n=19A117863