login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A000508 Generalized class numbers.
(Formerly M5324 N2315)
4
61, 2763, 38528, 249856, 1066590, 3487246, 9493504, 22634496, 48649086, 96448478, 179369856, 315621376, 530788622, 860061996, 1346126848, 2046820352, 3038120316, 4403100222, 6254596992, 8737505280, 11992903772 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=1..21.

D. Shanks, Generalized Euler and class numbers, Math. Comp. 21 1967 6890694.

D. Shanks, Corrigenda to: "Generalized Euler and class numbers", Math. Comp. 22 (1968), 699

D. Shanks, Generalized Euler and class numbers, Math. Comp. 21 (1967), 689-694; 22 (1968), 699. [Annotated scanned copy]

MATHEMATICA

amax = 25; km0 = 10; Clear[cc]; L[a_, s_, km_] := Sum[ JacobiSymbol[ -a, 2 k + 1]/(2 k + 1)^s, {k, 0, km}]; c[1, n_, km_] := 2 (2 n)! L[1, 2 n + 1, km] (2/Pi)^(2 n + 1) // Round; c[a_ /; a > 1, n_, km_] := (2 n)! L[a, 2 n + 1, km] (2 a/Pi)^(2 n + 1)/Sqrt[a] // Round; cc[km_] := cc[km] = Table[ c[a, 3, km], {a, 1, amax} ]; cc[km0]; cc[km = 2 km0]; While[cc[km] != cc[km/2, km = 2 km]]; A000508 = cc[km] (* Jean-Fran├žois Alcover, Feb 09 2016 *)

CROSSREFS

Cf. A000003, A000233, A000362.

Sequence in context: A038650 A224441 A078962 * A191092 A234028 A135647

Adjacent sequences:  A000505 A000506 A000507 * A000509 A000510 A000511

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jun 02 2000

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 20 12:57 EST 2019. Contains 320327 sequences. (Running on oeis4.)