a(n) = Sum_{1 <= x_1 <= x_2 <= x_3 <= x_4 <= x_5 <= x_6 <= x_7 <= n} gcd(x_1, x_2, x_3 , x_4, x_5, x_6, x_7, n).
A343521
a(n) = Sum_{1 <= x_1 <= x_2 <= x_3 <= x_4 <= x_5 <= x_6 <= x_7 <= n} gcd(x_1, x_2, x_3 , x_4, x_5, x_6, x_7, n).
Terms
- a(0) =1a(1) =9a(2) =38a(3) =130a(4) =334a(5) =846a(6) =1722a(7) =3572a(8) =6513a(9) =11806a(10) =19458a(11) =32948a(12) =50400a(13) =79290a(14) =117092a(15) =174256a(16) =245173a(17) =354249a(18) =480718a(19) =670420a(20) =891690a(21) =1203578a(22) =1560802a(23) =2076496a(24) =2630915a(25) =3416352a(26) =4285152a(27) =5461348a(28) =6724548a(29) =8490884
External references
- oeis: A343521