20189

Appears in sequences

• a(1) = 7; a(n+1) = a(n)-th nonprime, where nonprimes begin at 0.at n=39A025002
• a(n) = (15*n^4 + 22*n^3 + 45*n^2 + 14*n) / 24.at n=13A101166
• Expansion of Product_{k>=1} 1/(1-x^(3*k-2))^(3*k-2).at n=30A262947
• Expansion of Product_{k>0} (1+k^2*x^k)^(-1/k).at n=16A303354
• Numbers k such that 413*2^k+1 is prime.at n=21A323106
• a(n) is the number of 4 element sets of distinct integer sided trapezoids whose base angles are 60 degrees that fill an equilateral triangular grid of side n units.at n=46A389392