

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
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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) 689694.
D. Shanks, Corrigendum: Generalized Euler and class numbers. Math. Comp. 22, (1968) 699.
D. Shanks, Generalized Euler and class numbers, Math. Comp. 21 (1967), 689694; 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]] (* JeanFrançois 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



