A141391 a(n) is the smallest unused number such that the RMS (Root Mean Square) of a(1) through a(n) is an integer.

1, 7, 5, 11, 28, 14, 182, 70, 2, 66, 1518, 462, 1540, 616, 296, 600, 1950, 750, 10, 730, 2336, 876, 2436, 996, 3154, 1162, 5698, 210, 1554, 3234, 1638, 5382, 1872, 23088, 4368, 5934, 201, 4359, 77991, 7021, 13090, 4270, 12950, 74, 12802, 76466, 16954

Offset: 1

Author

Andrew Weimholt, Jun 29 2008

Keywords

• nonn

Comments

Actual RMS values are given by A141392

Examples

			a(4) = 11. Sqrt(mean(1^2, 7^2, 5^2, k^2)) is an integer for k in {5,11,37}. We have already used 5 for a(3), so 11 is the smallest value available for a(4).
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A141392, A141393, A141394, A140480.

Programs

Mathematica

s={1};Do[i=1;Until[!MemberQ[s,i]&&IntegerQ[RootMeanSquare[Append[s,i]]],i++];AppendTo[s,i],{n,46}];s (* James C. McMahon, Jul 24 2025 *)