61680

Appears in sequences

• Number of free subsets of multiplicative group of GF(2^n).at n=16A007230
• Numbers whose base-4 representation contains exactly four 0's and four 3's.at n=25A045085
• Solutions to phi(gpf(x)) - gpf(phi(x)) = 254 = c are special multiples of 257, x = 257k, where largest prime factors of factor k were observed from {2, 3, 5, 17}. See solutions to other even cases of c (=A070813): A007283 for 0, A070004 for 2, A070814 for 14, A070816 for 65534.at n=34A070815
• List of codewords in binary lexicode with Hamming distance 8 written as decimal numbers.at n=29A075940
• Numbers k such that phi(k) is a perfect 7th power.at n=25A078167
• a(n) = A080315(n) - 2^A000523(A080315(n)), i.e., the terms of A080315 without their most significant bit.at n=18A080316
• A014486-encoding of the Catalan mountain ranges with only even-length slopes allowed.at n=15A083932
• a(n) = sigma_3(n) - sigma_1(n).at n=37A092348
• Numbers whose set of base 16 digits is {0,F}, where F base 16 = 15 base 10.at n=10A097262
• Number of equicolored (unrooted) trees on 2n nodes.at n=8A119857
• a(0) = 0; for n>0, a(n) = period length of the decimal expansion of the number Sum_{i>=1} 2^(-n*i). Also period length of the fractions 1/b(n), where b(n) = 2*b(n-1) + 1, with b(1)=1.at n=39A136273
• A positive integer n is included if n written in binary can be subdivided into a number of runs all of equal-length, the first run from the left consisting of all 1's, the next run consisting of all 0's, the next run consisting of all 1's, the next run consisting of all 0's, etc.at n=47A140690
• Numbers such that every run length in base 2 is 4.at n=3A154806
• Numbers n such that n and n^4 are sums of two twin primes.at n=11A212430
• Numbers a(n) with property a(n) + a(n+4) = 2^(n+4) - 1 = A000225(n+4).at n=16A224520
• Rows of binary Walsh matrices interpreted as reverse binary numbers.at n=19A228539
• Number of length 1+2 0..n arrays with no three consecutive terms having the sum of any two elements equal to twice the third.at n=38A248462
• Positive integers n such that n=p+q for some primes p,q with pi(p)*pi(q) = sigma(n).at n=37A273286
• Number of subsets of {1..n} containing n whose mean is not an element.at n=17A327477
• a(n) = floor(n*2^n/(n + 1)).at n=16A350294