|
%I #18 Jan 11 2018 10:00:51
%S 1,8,18,36,50,90,98,160,171,250,242,392,338,490,500,656,578,882,722,
%T 1050,980,1210,1058,1640,1275,1690,1620,2058,1682,2522,1922,2688,2420,
%U 2890,2548,3726,2738,3610,3380,4328,3362,4900,3698,5082,4662,5290,4418,6688
%N a(n) = Sum_{d|n} max(d, n/d)^2.
%H Seiichi Manyama, <a href="/A297841/b297841.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = 2*A001157(n) - A297792(n).
%p f:= n -> add(max(d,n/d)^2, d = numtheory:-divisors(n)):
%p map(f, [$1..100]); # _Robert Israel_, Jan 10 2018
%t f[n_] := Block[{d = Divisors@ n}, Plus @@ (Max[#, n/#]^2 & /@ d)]; Array[f, 50] (* _Robert G. Wilson v_, Jan 07 2018 *)
%o (PARI) {a(n) = sumdiv(n, d, max(d, n/d)^2)}
%Y Sum_{d|n} max(d, n/d)^k: A117003 (k=1), this sequence (k=2), A297842 (k=3), A297843 (k=4), A297844 (k=5).
%Y Cf. A001157, A297792.
%K nonn
%O 1,2
%A _Seiichi Manyama_, Jan 07 2018
|
