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A111102
Cumulative sum of squares of Kolakoski sequence (A000002).
1
1, 5, 9, 10, 11, 15, 16, 20, 24, 25, 29, 33, 34, 35, 39, 40, 41, 45, 49, 50, 54, 55, 56, 60, 61, 65, 69, 70, 71, 75, 76, 77, 81, 82, 86, 90, 91, 95, 99, 100, 101, 105, 106, 110, 114, 115, 119, 120, 121, 125, 126, 127, 131, 135, 136, 140, 144, 145, 146, 150, 151, 155, 159, 160, 164, 168, 169, 170, 174
OFFSET
1,2
COMMENTS
a(n) is prime for n = 2, 5, 11, 17, 25, 29. a(n) is semiprime for n = 3, 4, 6, 10, 12, 13, 14, 15, 19, 22, 26, 27. a(n) is a perfect square for n = 1, 3, 7, 10, 19.
LINKS
FORMULA
a(n) = Sum_{i=1..n} A000002(i)^2.
MATHEMATICA
A000002[n_]:= If[n<3, Max[0, n], Module[{an = {1, 2, 2}, m = 3}, While[Length[an] < n, an = Join[an, Table[Mod[m, 2, 1], {an[[m]]}]]; m++]; an[[n]]]]; Table[Sum[A000002[j]^2, {j, n}], {n, 1, 70}] (* G. C. Greubel, Dec 18 2019; Somos code of A000002 *)
CROSSREFS
Cf. A000002.
Sequence in context: A268412 A043682 A335882 * A139456 A195684 A135980
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Oct 13 2005
STATUS
approved