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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 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

This constant is A275647 (which gives the sum of the reciprocals of the squares of nonprime numbers) minus 1.

LINKS

Table of n, a(n) for n=0..104.

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

Adjacent sequences:  A335586 A335587 A335588 * A335590 A335591 A335592

KEYWORD

nonn,cons

AUTHOR

Jon E. Schoenfield, Jan 26 2021

STATUS

approved

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Last modified October 22 16:15 EDT 2021. Contains 348174 sequences. (Running on oeis4.)