124020domain: NAppears in sequencesPartial sums of second pentagonal numbers with even index (A049453).at n=39A051895G.f. satisfies A(x) = 1 + x*(1 + x*A(x)^4)^5.at n=7A137965a(n) = A016755(n) - A001845(n).at n=26A188050Numbers k such that A051709(k)/A173557(k) is a positive natural number and a divisor of k.at n=28A344995