A244329 - OEIS

%I #17 Sep 01 2024 16:48:12

%S 0,0,0,0,1,0,2,1,2,2,4,1,5,3,4,3,7,3,8,4,6,6,10,4,9,7,8,6,13,5,14,7,

%T 10,10,12,6,17,11,12,8,19,8,20,10,12,14,22,8,20,12,17,13,25,11,20,12,

%U 19,18,28,9,29,19,18,15,24,14,32,17,24,16,34,12,35,23

%N a(n) = floor(antisigma(n) / sigma(n)) = floor(A024816(n) / A000203(n)).

%C RECORD transform of a(n) is A140475 (union of number 1 and primes >= 5).

%C Sequence of numbers n such that a(n) = floor(antisigma(n) / n) = A046022.

%C Sequence of numbers n such that a(n) = a(n+1) = A244666.

%H Paolo Xausa, <a href="/A244329/b244329.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A244327(n) - A244328(n) for n >= 7.

%e For n = 10; a(10) = floor(A024816(10) / A000203(10)) = floor(37 / 18) = 2.

%t A244329[n_] := Floor[(n*(n + 1)/2 - #)/#] & [DivisorSigma[1, n]];

%t Array[A244329, 100] (* _Paolo Xausa_, Sep 01 2024 *)

%o (Magma) [Floor(((n*(n+1)div 2)-SumOfDivisors(n)) div (SumOfDivisors(n))) : n in [1..1000]];

%Y Cf. A000203, A000217, A024816, A046022, A140475, A244327, A244328, A244666.

%K nonn

%O 1,7

%A _Jaroslav Krizek_, Jul 08 2014