20528

Appears in sequences

• Powers of cube root of 15 rounded up.at n=11A018020
• Fibonacci sequence beginning 3, 11.at n=17A022123
• a(n) = [ C(2n,n)/(n-1) ].at n=8A024499
• Numerators of continued fraction convergents to sqrt(57).at n=9A041098
• Numbers such that the nonzero product of the digits of its 4th power is also a 4th power.at n=9A066734
• Least k >= 6 such that A087666(k) = n.at n=22A087710
• Number of lower triangles of a 3 X 3 0..n array with each element differing from all of its diagonal, vertical, antidiagonal and horizontal neighbors by two or less.at n=20A195249
• Permutation of natural numbers: a(0)=0, a(1)=1, a(2n)=A005228(1+(a(n))), a(2n+1)=A030124(a(n)).at n=36A232752
• Lengths of runs of the initial digits of semiprimes in decimal representation, cf. A239634.at n=44A239639
• Numbers equal to the arithmetic derivative of their Euler totient function.at n=40A248815
• The smallest position with nim-value n in subtract-a-square game.at n=43A297963