|
Search: id:A064987
|
|
| |
|
| 1, 6, 12, 28, 30, 72, 56, 120, 117, 180, 132, 336, 182, 336, 360, 496, 306, 702, 380, 840, 672, 792, 552, 1440, 775, 1092, 1080, 1568, 870, 2160, 992, 2016, 1584, 1836, 1680, 3276, 1406, 2280, 2184, 3600, 1722, 4032, 1892, 3696, 3510, 3312, 2256, 5952
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Dirichlet convolution of sigma_2(n) with phi(n). - Vladeta Jovovic (vladeta(AT)Eunet.yu), Oct 27 2002
|
|
REFERENCES
|
B. C. Berndt, Ramanujan's theory of theta-functions, Theta functions: from the classical to the modern, Amer. Math. Soc., Providence, RI, 1993, pp. 1-63. MR 94m:11054. see page 43.
|
|
FORMULA
|
Multiplicative with a(p^e) = p^e*(p^(e+1)-1)/(p-1).
G.f.: Sum_{n>0} n^2*x^n/(1-x^n)^2. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Oct 27 2002
G.f. is phi_2, 1(x) where phi_{r, s}(x)=Sum_{n, m>0} m^r n^s x^{mn}. - Michael Somos, Apr 02 2003
G.f. is also (Q-P^2)/288 where P, Q are Ramanujan sums. - Michael Somos, Apr 02 2003
|
|
PROGRAM
|
(PARI) a(n)=if(n<1, 0, n*sigma(n))
|
|
CROSSREFS
|
Cf. A000203, A038040, A002618.
Cf. A000010, A001157.
Adjacent sequences: A064984 A064985 A064986 this_sequence A064988 A064989 A064990
Sequence in context: A009242 A032647 A086792 this_sequence A057341 A068412 A109510
|
|
KEYWORD
|
mult,nonn
|
|
AUTHOR
|
Vladeta Jovovic (vladeta(AT)Eunet.yu), Oct 30 2001
|
|
|
Search completed in 0.002 seconds
|
