20980

Appears in sequences

• a(n) = Sum_{k=0..floor((n+1)/2)} (k+1) * A008315(n, k).at n=13A027305
• Least K such that K*(3^(n+j))+1 is prime for j=0 to 4.at n=3A109854
• Let M(n) be the n X n matrix m(i,j)=min(i,j) for 1<=i,j<=n; then a(n) is the trace of M(n)^(-7).at n=7A114359
• Expansion of g.f.: 1/((1 - x^2 - x^3 - x^4 - x^5 - x^6 - x^7)*(1 + x + x^2 + x^3 + x^4 + x^5 - x^7)).at n=26A147605
• Number of ways to partition n into reduced fractions i/j with j <= n.at n=4A154886
• a(n) = 1000*n - 20.at n=20A157515
• Number of degree n polynomials p(x,y) with all coefficients 0 or 1 such that x+y=1 implies p(x,y)=1.at n=10A181496
• Row sums of A050157.at n=7A296771
• Number of cells in a regular 7-gon after n generations of mitosis.at n=24A349808
• T(n,k) is the number of permutations of [n] having exactly k pairs of integers i<j in [n] such that their cycle minima have opposite sorting order; triangle T(n,k), n>=0, 0<=k<=A125811(n)-1, read by rows.at n=50A381529