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A000233 Generalized class numbers.
(Formerly M2722 N1090)
5
1, 3, 8, 16, 30, 46, 64, 96, 126, 158, 216, 256, 302, 396, 448, 512, 636, 702, 792, 960, 1052, 1118, 1344, 1472, 1550, 1866, 1944, 2048, 2442, 2540, 2688, 3072, 3212, 3388, 3888, 4032, 4094, 4746, 4928, 5056, 5832, 5852, 5976, 6912, 7020, 7180, 8064, 8192 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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..48.

D. Shanks, Generalized Euler and class numbers. Math. Comp. 21 (1967) 689-694.

D. Shanks, Corrigendum: 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 = 50; nmax = 1; 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, n, km], {a, 1, amax}, {n, 0, nmax}]; cc[km0]; cc[ km = 2 km0]; While[cc[km] != cc[km/2, km = 2 km]]; A000233 = cc[km][[All, 2]] (* Jean-Fran├žois Alcover, Feb 06 2016 *)

CROSSREFS

Cf. A000508, A000362.

Sequence in context: A169947 A167616 A009439 * A002624 A293358 A227265

Adjacent sequences:  A000230 A000231 A000232 * A000234 A000235 A000236

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

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Last modified April 12 01:36 EDT 2021. Contains 342912 sequences. (Running on oeis4.)