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A274590 Numbers n such that n^2 - 1 is the average of two nonzero squares in exactly one way. 0
9, 19, 33, 35, 73, 99, 145, 161, 163, 195, 243, 393, 483, 513, 577, 721, 723, 1153, 1763, 2177, 2305, 2593, 4803, 5185, 5833, 6273, 6963, 7057, 7395, 8713, 9523, 9603, 10083, 12483, 13923, 14113, 15875, 17425, 17673, 19043, 19601, 20737, 26243 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

In other words, numbers n such that n^2 - 1 is the sum of two nonzero distinct squares in exactly one way. This explains why there are many common terms between this sequence and A050797.

LINKS

Table of n, a(n) for n=1..43.

EXAMPLE

9 is a term because 9^2 - 1 = (4^2 + 12^2) / 2.

CROSSREFS

Cf. A050797.

Sequence in context: A190513 A190576 A250663 * A051811 A034056 A195042

Adjacent sequences:  A274587 A274588 A274589 * A274591 A274592 A274593

KEYWORD

nonn

AUTHOR

Altug Alkan, Jun 29 2016

STATUS

approved

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Last modified September 27 13:03 EDT 2021. Contains 347688 sequences. (Running on oeis4.)