A071419 a(1)=1, a(n+1)=(a(n)+n)/2 if a(n)+n is even, a(n+1)=(3*(a(n)+n)+1)/2 otherwise.

1, 1, 5, 4, 4, 14, 10, 26, 17, 13, 35, 23, 53, 33, 71, 43, 89, 53, 107, 63, 125, 73, 143, 83, 161, 93, 179, 103, 197, 113, 215, 123, 233, 133, 251, 143, 269, 153, 287, 163, 305, 173, 323, 183, 341, 193, 359, 203, 377, 213, 395, 223, 413, 233, 431, 243, 449, 253

Offset

1,3

Comments

Let a(1) be any integer >=0, is there always a positive integer N such that if n>=N a(n+2)-a(n)= 10 or 18 (depending on the parity of n)?

Links

Table of n, a(n) for n=1..58.

Formula

For k>=1 a(2k+12)=13+10k, a(2k+11)=17+18k

Mathematica

nxt[{a_, b_}]:=If[EvenQ[a+b], {a+1, (a+b)/2}, {a+1, (3(b+a)+1)/2}]; Transpose[ NestList[nxt, {1, 1}, 60]][[2]] (* Harvey P. Dale, Apr 01 2012 *)

Crossrefs

Sequence in context: A340918 A244046 A255332 * A291069 A019117 A204372

Adjacent sequences: A071416 A071417 A071418 * A071420 A071421 A071422

Keyword

easy,nonn

Author

Benoit Cloitre, May 29 2002

Status

approved