a(n) = Sum_{1 <= i, j, k, l, m <= n} gcd(i,j,k,l,m).

Terms

a(0) =1a(1) =33a(2) =246a(3) =1060a(4) =3165a(5) =8091a(6) =17128a(7) =33936a(8) =60645a(9) =103825a(10) =164886a(11) =259368a(12) =381841a(13) =557595a(14) =784200a(15) =1091056a(16) =1462353a(17) =1968261a(18) =2554810a(19) =3327120a(20) =4230561a(21) =5361463a(22) =6644196a(23) =8302020a(24) =10113445a(25) =12352041a(26) =14873418a(27) =17924356a(28) =21225165a(29) =25341375