0,2

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

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

Equals Sum_{k>=1} 1/A002808(k)^2.

Equals 1/4^2 + 1/6^2 + 1/8^2 + 1/9^2 + 1/10^2 + ... = 0.19268664680716093796587180181377725504571855796690...

Cf. A275647.

Sequence in context: A154162 A046019 A021523 * A275647 A011436 A248317

Adjacent sequences: A335586 A335587 A335588 * A335590 A335591 A335592

nonn,cons

Jon E. Schoenfield, Jan 26 2021

approved