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A140612 Positive integers n such that both n and n+1 are the sum of 2 squares. 1
1, 4, 8, 9, 16, 17, 25, 36, 40, 49, 52, 64, 72, 73, 80, 81, 89, 97, 100, 116, 121, 136, 144, 145, 148, 169, 180, 193, 196, 225, 232, 233, 241, 244, 256, 260, 288, 289, 292, 305, 313, 324, 337, 360, 361, 369, 388, 400, 404, 409, 424, 441, 449, 457 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Equivalently, positive n such that n(n+1) is the sum of two squares.

Trivially, sequence includes all positive squares.

LINKS

Table of n, a(n) for n=1..54.

EXAMPLE

40 = 6^2 + 2^2, 41 = 5^2 + 4^2, so 40 is in the sequence.

CROSSREFS

Cf. A050795 (2a(n)+1), A001481, A002378, A000290.

Sequence in context: A153034 A106840 A242663 * A160053 A225353 A034023

Adjacent sequences:  A140609 A140610 A140611 * A140613 A140614 A140615

KEYWORD

easy,nonn

AUTHOR

Franklin T. Adams-Watters, May 19 2008

STATUS

approved

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Last modified March 26 22:28 EDT 2017. Contains 284138 sequences.