20490

Appears in sequences

• Numbers k such that k + sum of its prime factors = (k+1) + sum of its prime factors.at n=27A020700
• Numbers n such that n + sum of prime factors of n = (n+1) + sum of prime factors of (n+1).at n=22A075654
• Triangle read by rows: t(n,m) = Sum_{i=0..n} (-1)^(m-i)*Eulerian1(n-i+1, m-i) *Stirling2(n+i+1, i+1), where Eulerian1 are the Eulerian numbers of the first kind (A173018).at n=19A156364
• Antidiagonal sums of A147995 and A163545.at n=30A163484
• Generalized Narayana triangle for secant.at n=58A180959
• Generalized Narayana triangle for secant.at n=62A180959
• Number of (n+1) X (4+1) 0..3 arrays with every 2 X 2 subblock summing to 6 and no 2 X 2 subblock having exactly two nonzero entries.at n=4A251232
• Number of (n+1) X (5+1) 0..3 arrays with every 2 X 2 subblock summing to 6 and no 2 X 2 subblock having exactly two nonzero entries.at n=3A251233
• T(n,k) = Number of (n+1) X (k+1) 0..3 arrays with every 2 X 2 subblock summing to 6 and no 2 X 2 subblock having exactly two nonzero entries.at n=31A251236
• T(n,k) = Number of (n+1) X (k+1) 0..3 arrays with every 2 X 2 subblock summing to 6 and no 2 X 2 subblock having exactly two nonzero entries.at n=32A251236
• Composite numbers equal to the sum of the prime factors, with multiplicity, of the previous k numbers, for some k.at n=10A257525
• Numbers equal to the sum of the prime factors, with multiplicity, of the previous k numbers, for some k.at n=14A257976
• Pisot sequence T(5,13).at n=9A278764
• Numbers k such that sum of distinct primes dividing k is equal to the sum of proper divisors of k+1.at n=9A354603
• Expansion of 1/( (1 + x) * (1 - x^2*(1 + x)^3) ).at n=18A375364
• Expansion of g/(1 - x^4*g^4), where g = 1+x*g^2 is the g.f. of A000108.at n=10A391035