26818

Appears in sequences

• a(n) = n*(n + 1)*(n^2 - 3*n + 6)/8.at n=21A004255
• Numbers whose sum of divisors is a sixth power.at n=11A019424
• Number of distributive lattices; also number of paths with n turns when light is reflected from 11 glass plates.at n=5A030115
• Numbers whose sum of divisors is 6^6 = 46656.at n=8A048256
• Numbers k such that the first k septenary digits found in the decimal expansion of Pi form a prime.at n=7A065575
• Trisection of A007294.at n=41A073471
• Ordered product of the sides of primitive Pythagorean triangles divided by 60.at n=28A081752
• a(n) = Sum_{k=0..n-1} sigma(2k+1)*sigma_3(n-k).at n=10A081860
• Number of 5-tuples (v1,v2,v3,v4,v5) of nonnegative integers less than n such that v1 <= v5, v2 <= v5, v2 <= v4 and v3 <= v4.at n=10A085461
• Duplicate of A004255.at n=22A101357
• Numbers k such that k^3 contains a pandigital substring.at n=30A115933
• Number of compositions of n such that the smallest part is divisible by the number of parts.at n=49A171628
• Define two triangular arrays by: B(0,0)=C(0,0)=1, B(0,r)=C(0,r)=0 for r>0, C(t,-1)=C(t,0); and for t,r >= 0, B(t+1,r)=C(t,r-1)+2C(t,r)-B(t,r), C(t+1,r)=B(t+1,r)+2B(t+1,r+1)-C(t,r). Sequence gives array B(t,r) read by rows.at n=38A177011
• a(n) = n*(n + 1)*(5*n - 4)/2.at n=22A237616
• Number of partitions p of n such that max(p) - 3*min(p) is a part of p.at n=45A238627
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 283", based on the 5-celled von Neumann neighborhood.at n=33A271119
• E.g.f.: S(x,q) = Integral C(x,q) * C(q*x,q) dx, such that C(x,q)^2 - S(x,q)^2 = 1, where S(x,q) = Sum_{n>=0} sum_{k=0..n*(n+1)/2} T(n,k)*x^n*y^k/n!, as an irregular triangle of coefficients T(n,k) read by rows.at n=28A322219
• Index of record gaps between totient numbers.at n=12A383890