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A243582
Integers of the form 8k+7 (A004771) that cannot be written as sum of four distinct squares.
5
7, 15, 23, 31, 47, 55, 103
OFFSET
1,1
EXAMPLE
a(6) = 55 since 55 == 7 (mod 8) and all its representations as a sum of squares have duplicates, namely, 55=1^2+1^2+2^2+7^2, 55=1^2+2^2+5^2+5^2, 55=1^2+3^2+3^2+6^2.
KEYWORD
nonn,fini,full
AUTHOR
Walter Kehowski, Jun 08 2014
STATUS
approved