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A097274 Least integer "mod 2 prime signatures" k ordered by number of Pythagorean triples with leg = k. 3
1, 2, 3, 4, 6, 8, 9, 18, 16, 27, 54, 12, 15, 30, 32, 81, 162, 64, 243, 486, 128, 729, 1458, 24, 36, 45, 90, 256, 2187, 4374, 512, 6561, 13122, 1024, 19683, 39366, 48, 108, 135, 270, 2048, 59049, 118098, 4096, 177147, 354294, 72, 225, 450, 8192, 531441 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

COMMENTS

For n=2^a_0*p_1^a_1*...*p_n^a_n where p_i is odd prime and a_1>=a_2>=...>=a_n, define "mod 2 prime signature" to be ordered prime exponents (a_0,a_1,...,a_n).

Least integer with a given mod 2 prime signature is obtained by replacing p_1 with 3, p_2 with 5,..., p_n with n-th odd prime.

LINKS

Eric Weisstein's World of Mathematics, Pythagorean Triple.

EXAMPLE

Table begins:

0: 1,2,

1: 3,4,6,

2: 8,9,18,

3: 16,27,54,

4: 12,15,30,32,81,162,

5: 64,243,486,

6: 128,729,1458,

7: 24,36,45,90,256,2187,4374,

8: 512,6561,13122,

9: 1024,19683,39366,

10: 48,108,135,270,2048,59049,118098,

11: 4096,177147,354294,

12: 72,225,450,8192,531441,1062882,

CROSSREFS

Cf. A097272, A097273, A097275.

Sequence in context: A073667 A160256 A151545 * A121539 A122138 A047418

Adjacent sequences:  A097271 A097272 A097273 * A097275 A097276 A097277

KEYWORD

nonn,tabf

AUTHOR

Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 22 2004

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Last modified February 15 15:20 EST 2012. Contains 205823 sequences.