100667392domain: NAppears in sequencesa(n) is the sum of all integers from 2^(n-2)+1 to 2^(n-1).at n=13A049775Expansion of x*(1+5*x)/((1+2*x+1)*(1-4*x)).at n=14A117110a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) for n > 4, with first terms 1, 2, 4, 7.at n=27A135360a(n) = ((2^n)*((2^n)+1) - (2^(n-1))*((2^(n-1))+1))/2, a(1)=3.at n=13A158561