A180746 Partial sums of A004144.

1, 3, 6, 10, 16, 23, 31, 40, 51, 63, 77, 93, 111, 130, 151, 173, 196, 220, 247, 275, 306, 338, 371, 407, 445, 487, 530, 574, 620, 667, 715, 764, 818, 874, 931, 990, 1052, 1115, 1179, 1245, 1312, 1381, 1452, 1524, 1600, 1677, 1756, 1837, 1920, 2004, 2090, 2178

Offset: 1

Author

Jonathan Vos Post, Sep 19 2010

Keywords

• nonn

Crossrefs

Cf. A004144.

Programs

Mathematica

fQ[n_] := If[n > 1, First@ Union@ Mod[ First@# & /@ FactorInteger@ n, 4] != 1, True]; Accumulate@ Select[ Range@ 90, fQ]

Formula

a(n) = Sum_{i=1..n} A004144(i).

Extensions

a(21) and a(50) corrected by Georg Fischer, Aug 29 2020