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A354776
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Even numbers that are the sum of two squares; also numbers which are twice the sum of two squares.
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0
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0, 2, 4, 8, 10, 16, 18, 20, 26, 32, 34, 36, 40, 50, 52, 58, 64, 68, 72, 74, 80, 82, 90, 98, 100, 104, 106, 116, 122, 128, 130, 136, 144, 146, 148, 160, 162, 164, 170, 178, 180, 194, 196, 200, 202, 208, 212, 218, 226, 232, 234, 242, 244, 250, 256, 260, 272, 274, 288, 290, 292, 296, 298, 306, 314, 320
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OFFSET
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1,2
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COMMENTS
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This is both the even subsequence of A001481, and twice A001481. It is an easy exercise to show that these two definitions produce the same sequence.
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LINKS
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PROG
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(Python)
from itertools import count, islice
from sympy import factorint
def A354776_gen(): # generator of terms
return filter(lambda n:(lambda m:all(d & 3 != 3 or m[d] & 1 == 0 for d in m))(factorint(n//2)), count(0, 2))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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