divisor fanctions
kohmoto
zbi74583 at boat.zero.ad.jp
Sat Jun 11 06:39:04 CEST 2005
Neil.
I submitted sequences of Perfect Number using the following divisor
functions.
But I think I didn't submitted these divisor functions.
I suppose OEIS should have them too
%I A000001
%S A000001 1, 3, 4, 7, 6, 12, 8, 15, 10, 18, 12, 28, 14, 24, 24, 31, 18,
30, 20, 42
%N A000001 OrdinaryUnitarySigma(n) : If n=Product p_i^r_i then
OUSigma(n)=Sigma(2^r_1)*UnitarySigma(n/2^r_1)=(2^(r_1+1)-1)*Product(p_i^r_i+1),
p_i is not 2.
%e A000001
OUSigma(2^4*7^2)=Sigma(2^4)*UnitarySigma(7^2)=31*50=1550.
%O A000001 1,2
%Y A000001 A000002, A091321
%K A000001 nonn, mult,
%A A000001 Yasutoshi Kohmoto (zbi74583 at boat.zero.ad.jp)
%I A000002
%S A000002 1, 3, 4, 5, 6, 12, 8, 9, 13, 18, 12, 20, 14, 24, 24, 17, 18,
39, 20, 30
%N A000002 UnitaryOrdinarySigma(n) : If n=Product p_i^r_i then
UOSigma(n)=UnitarySigma(2^r_1)*Sigma(n/2^r_1)=(2^r_1+1)*Product
(p_i^(r_i+1)-1)/(p_i-1), p_i is not 2.
%e A000002
UOsigma(2^4*7^2)=UnitarySigma(2^4)*sigma(7^2)=17*57=969
%O A000002 1,2
%Y A000002 A000001, A092356
%K A000002 nonn, mult,
%A A000002 Yasutoshi Kohmoto (zbi74583 at boat.zero.ad.jp)
Yasutoshi
PS
Two divisor functions in my May,25 mail don't appear on OEIS.
Did you see the mail?
%I A000001
%S A000001 1, 4, 5, 8, 7, 20, 9, 16, 14, 28, 13, 40, 15, 36, 35, 32, 19,
56, 21, 56
%N A000001 (+2)Sigma(n) : If n=Product p_i^r_i then
(+2)Sigma(n)=Product (2+Sum p_i^s_i, s_i=1 to
r_i)=Product(1+(p_i^(r_i+1)-1)/(p_i-1)) ,
(+2)Sigma(1)=1
%e A000001 (+2)Sigma(6)=(2+2)*(2+3)=20.
%O A000001 1,2
%Y A000001 A000002, A052396
%K A000001 nonn, mult,
%A A000001 Yasutoshi Kohmoto (zbi74583 at boat.zero.ad.jp)
%I A000002
%S A000002 1, 4, 5, 6, 7, 20, 9, 10, 11, 28, 13, 30, 15, 36, 35, 18, 19,
44, 21, 42
%N A000002 (+2)UnitarySigma(n) : If n=Product p_i^r_i then
(+2)Sigma(n)=Product (2+p_i^r_i) ,
(+2)UnitarySigma(1)=1
%e A000002 (+2)UnitarySigma(12)=(2+3)*(2+4)=30.
%O A000002 1,2
%Y A000002 A000001, A054862
%K A000002 nonn, mult,
%A A000002 Yasutoshi Kohmoto (zbi74583 at boat.zero.ad.jp)
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