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A225866 Numbers n such that the sum of the numbers in the Collatz (3x+1) iteration of n is a perfect square. 1
1, 3, 5, 33, 60, 245, 304, 372, 1265, 1568, 1756, 1799, 1856, 2409, 2532, 2976, 3100, 3281, 3376, 3394, 3813, 5637, 5972, 6147, 6538, 7213, 7299, 7896, 7966, 8371, 10419, 11526, 13411, 13856, 14168, 15024, 15283, 15709, 16506, 16577, 16916, 19212, 19829, 21372 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..1000

EXAMPLE

60 is in the sequence because 60 + 30 + 15 + 46 + 23 + 70 + 35 + 106 + 53 + 160 + 80 + 40 + 20 + 10 + 5 + 16 + 8 + 4 + 2 + 1 = 784 = 28^2.

MATHEMATICA

collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #>1&]; Select[Range[22000], IntegerQ[Sqrt[Total[collatz[#]]]]&]

CROSSREFS

Cf. A033493.

Sequence in context: A235267 A284379 A103010 * A263295 A222484 A222630

Adjacent sequences:  A225863 A225864 A225865 * A225867 A225868 A225869

KEYWORD

nonn

AUTHOR

Michel Lagneau, May 18 2013

STATUS

approved

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Last modified May 21 11:54 EDT 2019. Contains 323443 sequences. (Running on oeis4.)