A363031 - OEIS

%I #34 Sep 07 2023 12:47:59

%S 1,8,14,20,31,32,38,44,57,72,62,68,74,80,108,112,98,104,110,144,133,

%T 128,160,140,180,152,158,164,183,248,182,216,194,200,252,212,256,224,

%U 230,288,242,280,288,304,324,272,278,284,307,360,352,308,314,360,434,332,338,400,350,432,381,368,374,380,576,432

%N a(n) = sigma(6*n+1). Sum of the divisors of 6*n+1, n >= 0.

%C The sum of divisors function A000203 seems to behave with a certain periodicity of period 6.

%H Michael De Vlieger, <a href="/A363031/b363031.txt">Table of n, a(n) for n = 0..9999</a>

%F a(n) = A000203(6*n+1).

%F a(n) = A000203(A016921(n)).

%t Array[DivisorSigma[1, 6 # + 1] &, 66, 0] (* _Michael De Vlieger_, Aug 27 2023 *)

%o (PARI) a(n) = sigma(6*n+1); \\ _Michel Marcus_, Aug 28 2023

%o (Python)

%o from sympy import divisor_sigma

%o def A363031(n): return divisor_sigma(6*n+1) # _Chai Wah Wu_, Sep 07 2023

%Y Partial sums give A363161.

%Y Cf. A000203, A016921, A224613.

%K nonn,easy

%O 0,2

%A _Omar E. Pol_, May 18 2023