199584

Appears in sequences

• Apéry numbers: n^3*C(2n,n).at n=6A005429
• Numbers k such that the set of prime divisors of k is equal to the set of prime divisors of sigma(k).at n=27A027598
• Expansion of e.g.f.: (1-x)^(-1/2)*exp(-x/2 -x^2/4 -x^3/6 -x^4/8).at n=10A053533
• Denominators of terms in series expansion of arcsin(arctan(x)) - arctan(arcsin(x)).at n=6A096722
• Denominator of Cotesian number C(n,2).at n=8A100646
• a(n) = binomial(n+2,2) * binomial(n+7,2).at n=26A104676
• a(n) = C(n+5,5) * C(n+7,7).at n=5A105948
• a(n) = binomial(n+5, 5) * binomial(n+7, 5).at n=5A107396
• Quasi-mirror of A062196 formatted as a triangular array.at n=50A124051
• Irregular triangle, read by rows, T(n, k) = binomial(2*n, k)*binomial(2*k, k).at n=41A156789
• Numbers n for which sigma(n)/n=k+2/3 with integer k.at n=6A160321
• Mirror of the triangle A193724.at n=49A193725
• Numbers n such that gcd(sigma(n), n) > gcd(sigma(m), m) for all m < n.at n=14A216793
• Numbers k that divide 3*sigma(k).at n=21A245774
• Numbers k such that A017666(k) = denominator(sigma(k)/k) = 3.at n=12A245775
• Integers k such that numerator and denominator of sigma(k)/k are both prime.at n=21A247086
• Numbers k such that k = Sum_{i=1..j} (d_i mod d), where d_i are their aliquot parts and d is one of them.at n=22A265646
• Average of amicable pairs (x,y), ordered by the smaller value x given in A002025.at n=21A275315
• Average of amicable pairs (x,y), ordered by the sum x+y given in A259953.at n=21A275316
• Numbers m such that m*p is divisible by m-p, where m > p > 0 and p = A007954(m) = the product of digits of m.at n=20A330880