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A108269
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Numbers of the form (2*m - 1)*4^k where m >= 1, k >= 1.
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9
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4, 12, 16, 20, 28, 36, 44, 48, 52, 60, 64, 68, 76, 80, 84, 92, 100, 108, 112, 116, 124, 132, 140, 144, 148, 156, 164, 172, 176, 180, 188, 192, 196, 204, 208, 212, 220, 228, 236, 240, 244, 252, 256, 260, 268, 272, 276, 284, 292, 300, 304, 308, 316, 320, 324, 332
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OFFSET
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1,1
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COMMENTS
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Numbers of terms in nonnegative integer sequences the sum of which is never a square.
The sum of a sequence of consecutive nonnegative integers starting with k is never a square for any k, if and only if the number of the terms in the sequence can be expressed as (2*m - 1) * 2^(2*n), m and n being any positive integers. (Proved by Alfred Vella, Jun 14 2005.)
Even numbers whose binary representation ends in an even number of zeros. - Amiram Eldar, Jan 12 2021
Numbers k for which the parity of k is equal to that of A048675(k).
A multiplicative semigroup; if m and n are in the sequence then so is m*n. (End)
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LINKS
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FORMULA
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EXAMPLE
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a( 1, 1 ) = 4, a( 2, 1) = 12, etc.
For a( 1, 1 ): the sum of 4 consecutive nonnegative integers (4k+6, if the first term is k) is never a square.
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MATHEMATICA
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Select[2 * Range[200], EvenQ @ IntegerExponent[#, 2] &] (* Amiram Eldar, Jan 12 2021 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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Andras Erszegi (erszegi.andras(AT)chello.hu), May 30 2005
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EXTENSIONS
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STATUS
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approved
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