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A000233
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Generalized class numbers.
(Formerly M2722 N1090)
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5
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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)
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OFFSET
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1,2
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REFERENCES
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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).
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LINKS
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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]
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MATHEMATICA
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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-François Alcover, Feb 06 2016 *)
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CROSSREFS
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Cf. A000508, A000362.
Sequence in context: A169947 A167616 A009439 * A002624 A293358 A227265
Adjacent sequences: A000230 A000231 A000232 * A000234 A000235 A000236
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane
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EXTENSIONS
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More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jun 02 2000
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STATUS
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approved
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