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A335589
Decimal expansion of the sum of the reciprocals of the squares of composite numbers.
1
1, 9, 2, 6, 8, 6, 6, 4, 6, 8, 0, 7, 1, 6, 0, 9, 3, 7, 9, 6, 5, 8, 7, 1, 8, 0, 1, 8, 1, 3, 7, 7, 7, 2, 5, 5, 0, 4, 5, 7, 1, 8, 5, 5, 7, 9, 6, 6, 9, 0, 6, 0, 1, 5, 9, 9, 9, 1, 3, 9, 2, 9, 9, 0, 1, 8, 8, 4, 2, 4, 4, 3, 0, 3, 9, 2, 8, 9, 9, 9, 9, 3, 8, 4, 6, 7, 1, 3, 5, 6, 2, 6, 4, 8, 5, 1, 8, 4, 7, 0, 8, 1, 1, 9, 8
OFFSET
0,2
COMMENTS
This constant is A275647 (which gives the sum of the reciprocals of the squares of nonprime numbers) minus 1.
FORMULA
Equals Sum_{k>=1} 1/A002808(k)^2.
EXAMPLE
Equals 1/4^2 + 1/6^2 + 1/8^2 + 1/9^2 + 1/10^2 + ... = 0.19268664680716093796587180181377725504571855796690...
CROSSREFS
Cf. A275647.
Sequence in context: A154162 A046019 A021523 * A275647 A011436 A248317
KEYWORD
nonn,cons
AUTHOR
Jon E. Schoenfield, Jan 26 2021
STATUS
approved