285600

Appears in sequences

• Sigma unitary-sigma perfect numbers: numbers m which satisfy the following equation for some integer k: sigma(usigma(m)) = k*m where usigma(m) is sum of unitary divisors of m.at n=31A083288
• Triangle T(n,k), read by rows, given by (2,0,3,0,4,0,5,0,6,0,7,0,8,0,9,...) DELTA (2,1,3,2,4,3,5,4,6,5,7,6,8,7,9,...) where DELTA is the operator defined in A084938.at n=32A199400
• Number of integers k^6 that divide 1!*2!*3!*...*n!.at n=21A248824
• Terms satisfy: a(2*n) = a(n)*b(n) and a(2*n+1) = a(n)*b(n+1) for n>=0 with a(0)=1, where A(x)^2 = Sum_{n>=0} b(n)*x^n and g.f. A(x) = Sum_{n>=0} a(n)*x^n.at n=15A257889
• Numbers m such that A049417(A049417(m)) = k*m for some k where A049417 is the infinitary sigma function.at n=23A318182
• a(n) is the least k such that A049417(A049417(k)) = n*k, where A049417 is the infinitary sigma function, or 0 if no such k exists.at n=8A318272
• Number of regions in a "frame" of size n X n (see Comments for definition).at n=24A331776
• Numbers m such that A188999(A034448(m)) = k*m for some k, where A034448 and A188999 are respectively the unitary and the bi-unitary sigma function.at n=43A369205