A275532 Possible values for sum of numbers in Collatz trajectory (A033493), sorted into ascending order.

1, 3, 7, 15, 31, 36, 46, 49, 55, 63, 66, 67, 91, 106, 119, 127, 139, 145, 148, 186, 190, 197, 214, 235, 248, 255, 259, 274, 281, 288, 301, 302, 316, 325, 330, 339, 346, 357, 386, 393, 399, 413, 427, 442, 452, 465, 497, 498, 500, 505, 509, 511, 519, 535, 540, 557

Offset: 1

Author

Jaroslav Krizek, Jul 31 2016

Keywords

• nonn

Comments

Values a(n) such that a(n) = A033493(x) = A033493(y) for distinct numbers x and y: 442, 609, 633, 724, 904, 925, ...

Crossrefs

Cf. A033493, A275531.

Programs

Magma

Set(Sort([&+[k eq 1 select n else IsOdd(Self(k-1)) and not IsOne(Self(k-1)) select 3*Self(k-1)+1 else Self(k-1) div 2: k in [1..5*n]]: n in [1..2^10] | &+[k eq 1 select n else IsOdd(Self(k-1)) and not IsOne(Self(k-1)) select 3*Self(k-1)+1 else Self(k-1) div 2: k in [1..5*n]] le 2^10]))

Mathematica

Take[#, 56] &@ Union@ Table[Total@ FixedPointList[Which[# == 1, 1, OddQ@ #, 3 # + 1, True, #/2] &, n] - 1, {n, 10^3}] (* Michael De Vlieger, Aug 02 2016 *)