68931domain: NAppears in sequencesNumerators of the continued fraction convergents of the decimal concatenation of the prime-indexed primes.at n=17A128850a(n) = (1+n)*(9 + 11*n + 4*n^2)/3.at n=36A172482G.f.: Product_{k>=1} 1/(1-x^k)^(2*k-1).at n=16A253289Number of regions in an equilateral triangle "frame" of size n.at n=18A328526