OFFSET
1,2
COMMENTS
A rational approximation (correct up to the 9th decimal digit) is 22781/62182.
Continued fraction: [0, 2, 1, 2, 1, 2, 3, 3, 1, 8, 5, 2, 1, 14,...].
EXAMPLE
Decimal expansion of Sum_{k=1..oo}{1/A045926(k)^2} = 1/2^2 + 1/4^2 + 1/6^2 + 1/8^2 + 1/22^2 + 1/24^2 + 1/26^2 + ... = 0.3663600397195232951718825089674124266251739503421187600...
MAPLE
P:=proc(q) local a, b, k, ok, n; a:=0; for n from 2 by 2 to q do ok:=1; b:=n;
for k from 1 to ilog10(n)+1 do if (b mod 10)=0 or ((b mod 10) mod 2)=1 then ok:=0;
break; else b:=trunc(b/10); fi; od; if ok=1 then a:=a+(1/n)^2; fi; od;
print(evalf(a, 200)); end: P(10^9);
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Paolo P. Lava, May 25 2015
STATUS
approved