A002147 Largest prime == 7 (mod 8) with class number 2n+1. (Formerly M4402 N1857)

7, 31, 127, 487, 1423, 1303, 2143, 2647, 4447, 5527, 5647, 6703, 5503, 11383, 8863, 13687, 13183, 12007, 22807, 18127, 21487, 22303, 29863, 25303, 27127

Offset

0,1

Comments

Apr 14 2008: David Broadhurst says: I computed class numbers for prime discriminants with |D| < 10^9, but stopped when the first case with |D| > 5*10^8 was observed. That factor of 2 seems to me to be a reasonable margin of error, when you look at the pattern of what is included.

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

David Broadhurst, Table of n, a(n) for n = 0..2246 (conjectural; see comment).

D. Shanks, Review of R. B. Lakein and S. Kuroda, Tables of class numbers h(-p) for fields Q(sqrt(-p)), p <= 465071, Math. Comp., 24 (1970), 491-492.

Crossrefs

Cf. A002146.

Sequence in context: A036280 A153005 A056909 * A169785 A255282 A303449

Adjacent sequences: A002144 A002145 A002146 * A002148 A002149 A002150

Keyword

nonn

Author

N. J. A. Sloane

Status

approved