A054788 Earliest sequence with a(a(n))=8n.

0, 2, 8, 4, 24, 6, 40, 9, 16, 56, 11, 80, 13, 96, 15, 112, 64, 18, 136, 20, 152, 22, 168, 25, 32, 184, 27, 208, 29, 224, 31, 240, 192, 34, 264, 36, 280, 38, 296, 41, 48, 312, 43, 336, 45, 352, 47, 368, 320, 50, 392, 52, 408, 54, 424, 57, 72, 440, 59, 464, 61, 480, 63, 496

Offset

0,2

Links

Table of n, a(n) for n=0..63.

Index entries for sequences of the a(a(n)) = 2n family

Mathematica

nmax = 63; amax = 8*nmax; t = {{0, a[0] = 0}, {1, a[1] = 2}, {2, a[2]}}; While[ !FreeQ[t, a], t = Table[{n, a[n]}, {n, 0, nmax}]; n = Select[t, !IntegerQ[ #[[2]] ] &, 1][[1, 1]]; t2 = Union[ Flatten[ Append[ Select[ t, IntegerQ[ #[[2]] ] &], n]]]; an = If[n == 2, 8, Select[ Complement[ Range[ Max[t2] ], t2], Mod[#, 8] != 0 &, 1][[1]] ]; a[n] = an; While[ an < amax, an = a[n = an] = 8 n]]; Table[ a[n], {n, 0, nmax}] (* Jean-François Alcover, Jan 11 2012 *)

Crossrefs

Cf. A002516, A002517, A002518, A007379.

Sequence in context: A019193 A369178 A253884 * A193851 A276624 A193847

Adjacent sequences: A054785 A054786 A054787 * A054789 A054790 A054791

Keyword

nice,nonn

Author

Henry Bottomley, Apr 27 2000

Status

approved