42020

Appears in sequences

• n written in fractional base 6/4.at n=30A024637
• Number of proper factorizations of p1^n*p2^3, where p1 and p2 are distinct primes.at n=22A031126
• Number of ways to write n as an ordered sum of 1s, 2s, 3s and 4s such that no 2 precedes any 1 and no 3 precedes any 1 or 2.at n=28A123569
• A Catalan transform of [x^n](1/(1-2x-2x^2)) (A002605).at n=8A155084
• a(n) = 25*n^2 - 5.at n=40A158446
• Number of (w,x,y,z) with all terms in {0,...,n} and |w-x|<|x-y|<|y-z|.at n=22A212902
• Start with 0. Successive digits in the sequence must differ by 2. Adjoin the smallest number not yet in the sequence.at n=44A228327
• Even numbers such that the sum of the even divisors and the sum of the odd divisors are a square or a cube.at n=31A263695
• Numbers n such that n and n+1 both have 24 divisors.at n=22A274362
• Numbers k such that k and k+1 both have the prime signature (2,1,1,1) (A189982).at n=9A336658
• Numbers k such that sigma(k) = psi(k) + tau(k)^3.at n=15A390297