18400

Appears in sequences

• Theta series of D*_25 lattice.at n=12A022078
• a(n) = Sum_{k=1..n} k*[ (n/k)*[ (n/k)*[ n/k ] ] ].at n=22A024933
• Expansion of (theta_3(z)*theta_3(5z)+theta_2(z)*theta_2(5z))^4.at n=31A028589
• Theta series of odd 8-dimensional 5-modular lattice O(5).at n=31A029719
• Decimal part of cube root of a(n) starts with 4: first term of runs.at n=25A034130
• A049031/2.at n=31A049032
• Engel expansion of Sum_{k>=0} 1/(9 + k)^k.at n=12A063192
• Numbers that define integer Heronian triangles [prime(a(n)), prime(a(n)+1), A068965(n)] with area A068966(n).at n=22A068964
• If X_1, ..., X_n is a partition of a 2n-set X into 2-blocks then a(n) is equal to the number of 3-subsets of X containing none of X_i, (i=1,...,n).at n=22A130809
• Number of permutations in S_n avoiding 5134{bar 2} (i.e., every occurrence of 5134 is contained in an occurrence of a 51342).at n=8A137537
• Numbers p^5*q^2*r where p, q, r are 3 distinct primes.at n=33A179691
• Wiener index of the n-sunlet graph.at n=29A180574
• Number of Carmichael numbers (A002997) less than 2^n.at n=42A225005
• Number of (n+2)X(1+2) 0..3 arrays with every 3X3 subblock row and column sum not 2 4 5 or 7 and every diagonal and antidiagonal sum 2 4 5 or 7.at n=5A251869
• Number of (n+2)X(6+2) 0..3 arrays with every 3X3 subblock row and column sum not 2 4 5 or 7 and every diagonal and antidiagonal sum 2 4 5 or 7.at n=0A251874
• T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row and column sum not 2 4 5 or 7 and every diagonal and antidiagonal sum 2 4 5 or 7.at n=15A251876
• T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row and column sum not 2 4 5 or 7 and every diagonal and antidiagonal sum 2 4 5 or 7.at n=20A251876
• Numbers n such that the decimal number concat(5,n) is a square.at n=32A273360
• Number of 3-abelian equivalence classes of words of length n over a binary alphabet.at n=25A289657
• p-INVERT of (1,1,1,1,1,...), where p(S) = (1 - S)*(1 - 3*S).at n=6A291009