A262519 Odd bisection of A155043.

1, 2, 3, 4, 3, 4, 5, 5, 6, 7, 7, 8, 6, 9, 10, 11, 11, 12, 13, 13, 14, 15, 14, 15, 10, 16, 17, 17, 18, 19, 20, 19, 21, 22, 22, 23, 24, 23, 25, 26, 15, 16, 16, 17, 18, 18, 19, 19, 20, 20, 21, 22, 21, 22, 23, 23, 24, 24, 24, 25, 21, 26, 22, 23, 23, 24, 24, 24, 25, 26, 26, 27, 27, 27, 28, 29, 28, 30, 31, 31, 32, 33, 32, 33, 28, 33, 34, 29, 35, 36, 37, 37

Offset: 0

Author

Antti Karttunen, Oct 02 2015

Keywords

• nonn

Comments

Number of steps needed to reach zero when starting from k = 2*n + 1 and repeatedly applying the map that replaces k by k - d(k), where d(k) is the number of divisors of k (A000005).

Links

• Antti Karttunen, Table of n, a(n) for n = 0..10000
• A. Karttunen, Ratio a(n)/A262518(n) drawn with the help of OEIS Plot2-script

Crossrefs

Cf. A000005, A049820, A155043, A262518, A262520, A262521, A262681.

Programs

Mathematica

Table[Length[NestWhileList[#-DivisorSigma[0,#]&,n,#!=0&]]-1,{n,1,200,2}] (* Harvey P. Dale, Aug 31 2017 *)

Scheme

(define (A262519 n) (A155043 (+ n n 1)))

Formula

a(n) = A155043(2*n + 1).