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A200977 Smallest number expressible in the form a^2 + 2b^2, with positive integers a and b, in exactly n ways. 0
3, 27, 99, 297, 891, 1683, 8019, 5049, 18513, 15147, 649539, 31977, 314721, 136323, 166617, 95931, 10673289, 351747, 64304361, 287793, 1499553, 8450649, 127680201, 863379, 20160657, 99379467, 5979699, 5180274, 1235641473, 3165723, 50984802, 3933171 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Incidentally all terms are multiples of 3.

LINKS

Table of n, a(n) for n=1..32.

EXAMPLE

3 = 1+2*1^2.

27 = 3+2*3^2 = 5^2+2*1^2.

99 = 1+2*7^2 = 7^2+2*5^2 = 9^2+2*3^2.

CROSSREFS

Cf. A154777 (numbers of the form a^2 + 2b^2 with positive integers a, b).

Sequence in context: A318908 A343135 A343105 * A302525 A303407 A173491

Adjacent sequences:  A200974 A200975 A200976 * A200978 A200979 A200980

KEYWORD

nonn

AUTHOR

Zak Seidov, Nov 29 2011

STATUS

approved

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Last modified August 16 00:08 EDT 2022. Contains 356150 sequences. (Running on oeis4.)