A217736 Sum of first n squares of semiprimes.

16, 52, 133, 233, 429, 654, 1095, 1579, 2204, 2880, 3969, 5125, 6350, 7794, 9315, 11431, 13832, 16433, 19458, 22707, 26071, 29915, 34140, 38901, 44377, 50306, 57030, 64255, 71651, 79220, 87501, 96150, 104986, 114011, 125247, 137568, 150793, 164717, 178878

Offset

1,1

Comments

There are 68 such numbers less than one million; a(68) = 988849.

Links

Christian N. K. Anderson, Table of n, a(n) for n = 1..10000

Example

a(3) = 4^2 + 6^2 + 9^2 = 133.

Mathematica

Accumulate[Select[Range[200], PrimeOmega[#]==2&]^2] (* Harvey P. Dale, Mar 13 2018 *)

Crossrefs

Cf. A062198. Equals sum(A001358^2), and sum(A074985).

Sequence in context: A241490 A009931 A009936 * A211578 A211592 A235653

Adjacent sequences: A217733 A217734 A217735 * A217737 A217738 A217739

Keyword

nonn

Author

Kevin L. Schwartz and Christian N. K. Anderson, Mar 22 2013

Status

approved