A071418 a(1)=0, a(n+1)=(a(n)+n)/2 if a(n)+n is even, a(n+1)=(3*(a(n)+n)+1)/2 otherwise.

0, 2, 2, 8, 6, 17, 35, 21, 44, 80, 45, 28, 20, 50, 32, 71, 131, 74, 46, 98, 59, 40, 31, 27, 77, 51, 116, 215, 365, 197, 341, 186, 109, 71, 158, 290, 163, 100, 69, 54, 47, 44, 43, 43, 131, 88, 67, 57, 158, 311, 542, 890, 471, 262, 158, 320, 188, 368, 213, 136, 98

Offset

1,2

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

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

If k>=0, a(2k+5432)=27113+10k, a(2k+5433)=48815+18k.

Mathematica

nxt[{n_, a_}]:={n+1, If[EvenQ[a+n], (a+n)/2, (3(a+n)+1)/2]}; Transpose[ NestList[ nxt, {1, 0}, 70]][[2]] (* Harvey P. Dale, Mar 24 2015 *)

Crossrefs

Sequence in context: A344601 A067436 A285114 * A353268 A245582 A361790

Adjacent sequences: A071415 A071416 A071417 * A071419 A071420 A071421

Keyword

easy,nonn

Author

Benoit Cloitre, May 29 2002

Status

approved