cp's OEIS Frontend

A054025 Sum of divisors of n read modulo (number of divisors of n).

%I A054025 #28 Oct 27 2023 22:00:46
%S A054025 0,1,0,1,0,0,0,3,1,2,0,4,0,0,0,1,0,3,0,0,0,0,0,4,1,2,0,2,0,0,0,3,0,2,
%T A054025 0,1,0,0,0,2,0,0,0,0,0,0,0,4,0,3,0,2,0,0,0,0,0,2,0,0,0,0,2,1,0,0,0,0,
%U A054025 0,0,0,3,0,2,4,2,0,0,0,6,1,2,0,8,0,0,0,4,0,6,0,0,0,0,0,0,0,3,0,1,0,0,0,2,0
%N A054025 Sum of divisors of n read modulo (number of divisors of n).
%C A054025 a(A003601(n)) = 0; a(A049642(n)) > 0. [_Reinhard Zumkeller_, Jan 06 2012]
%H A054025 Reinhard Zumkeller, <a href="/A054025/b054025.txt">Table of n, a(n) for n = 1..10000</a>
%F A054025 a(n) = A000203(n) mod A000005(n), sigma(n) mod tau(n).
%p A054025 with(numtheory): seq(sigma(i) mod tau(i),i=1..120);
%t A054025 Table[Mod[DivisorSigma[1,n],DivisorSigma[0,n]],{n,110}] (* _Harvey P. Dale_, Nov 16 2011 *)
%o A054025 (Haskell)
%o A054025 import Data.List (genericIndex)
%o A054025 a054025 n = genericIndex a054025_list (n-1)
%o A054025 a054025_list = zipWith mod a000203_list a000005_list
%o A054025 -- _Reinhard Zumkeller_, Jul 28 2014, Jan 06 2012
%o A054025 (PARI) vector(90, n, sigma(n) % numdiv(n)) \\ _Michel Marcus_, Aug 15 2015
%Y A054025 Cf. A000005, A000203.
%Y A054025 Cf. A003601, A049642, A245656.
%K A054025 nonn
%O A054025 1,8
%A A054025 _Asher Auel_, Jan 19 2000