20390

Appears in sequences

• Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite BEA = Beta Na7[Al7Si57O128] starting with a T1 atom.at n=13A019067
• Number of primes p between powers of 2, 2^n < p <= 2^(n+1).at n=18A036378
• Transform of the finite sequence (1, 0, -1, 0, 1, 0, -1) by the T_{0,0} transformation (see link).at n=13A159349
• a(n) = the number of noncomposites (primes or 1) that are n digits long when written in binary.at n=18A162145
• Number of binary strings of length n with equal numbers of 0001 and 0101 substrings.at n=16A164158
• Least positive integer k such that 1 + 1/2 + ... + 1/k > n/2.at n=20A226161
• a(n) = A342001(A342456(n)); "wild part" of the arithmetic derivative of A342456(n).at n=58A342463
• Number of n-bit primes.at n=18A374403