A029724 Odd numbers congruent to 7 mod 8 such that (2^(h(-n)+2)-n) is a square, where h(-n) is the class number.

7, 15, 23, 31, 39, 47, 55, 63, 71, 79, 87, 103, 127, 135, 151, 175, 183, 199, 207, 223, 247, 255, 271, 295, 343, 367, 375, 463, 487, 511, 583, 727, 751, 823, 847, 967, 1023, 1087, 1255, 1303, 1423, 1527, 2047, 2143, 3063, 3343, 4447, 5503

Offset

1,1

Links

Table of n, a(n) for n=1..48.

Prog

(PARI) forstep(n=7, 1e4, 8, if(issquare(2^(qfbclassno(-n)+2)-n), print1(n", "))) \\ Charles R Greathouse IV, May 08 2011

Crossrefs

Sequence in context: A017149 A133655 A004771 * A194400 A177768 A243582

Adjacent sequences: A029721 A029722 A029723 * A029725 A029726 A029727

Keyword

nonn

Author

Eric Rains (rains(AT)caltech.edu)

Status

approved