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A002052 Prime determinants of forms with class number 2.
(Formerly M4339 N1816)
2
3, 7, 11, 19, 23, 31, 43, 47, 59, 67, 71, 83, 103, 107, 127, 131, 139, 151, 163, 167, 179, 191, 199, 211, 227, 239, 251, 263, 271, 283, 307, 311, 331, 347, 367, 379, 383, 419 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The Suryanarayana paper contains these errors: In section 2, list (1) omits 3 and an asterisk should follow 1987; list (2) should include neither 3203 nor 3271. Section 3 should say "Of the 339 primes d == 3 (4) up to 5000, 289 primes satisfy h(d) = 2, while 50 do not." (correcting all three counts) - Rick L. Shepherd, Apr 29 2015

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

Rick L. Shepherd, Table of n, a(n) for n = 1..10000

M. Suryanarayana, Positive determinants of binary quadratic forms whose class-number is 2, Proceedings of the Indian Academy of Sciences. Section A, 2 (1935), 178-179.

PROG

(PARI) {QFBclassno(D) = qfbclassno(D) * if(D < 0 || norm(quadunit(D)) < 0, 1, 2);

n=0; forprime(p=3, 291619, if(p%4 == 3 && QFBclassno(4*p) == 2, n++; write("b002052.txt", n, " ", p)))} \\ Rick L. Shepherd, Apr 29 2015

CROSSREFS

Subsequence of A002145.

Sequence in context: A181516 A285015 A002145 * A092109 A117991 A118260

Adjacent sequences:  A002049 A002050 A002051 * A002053 A002054 A002055

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Term 3 added by Rick L. Shepherd, Apr 29 2015

STATUS

approved

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Last modified December 12 23:51 EST 2018. Contains 318081 sequences. (Running on oeis4.)