A189941 Numbers n such that n''' = n''+ 1 where n'' and n''' are respectively the second and the third arithmetic derivative of n.

186, 258, 322, 338, 3866, 4326, 4775, 18830, 19122, 27586, 34330, 34538, 41626, 46762, 49858, 49922, 54298, 55810, 70510, 82122, 86938, 89102, 101042, 101706, 106442, 110510, 112910, 118586, 120822, 129722, 133430, 134714, 150742, 157362, 158235, 163410

Offset

1,1

Comments

The second arithmetic derivative of a(n) is a Giuga's number A007850 (solution of n'=n+1).

Links

Donovan Johnson, Table of n, a(n) for n = 1..673

Example

186'= 161; 186"=161' = 30; 186"'=30'= 31-> 186'''= 186" +1 -> a(1)=186.

Maple

Using Porter's code from A003415 der:=n->n*add(op(2, p)/op(1, p), p=ifactors(n)[2])
for i from 1 to n do a:=der(der(der(i)))-der(der(i))-1: if a=0 then j:=j+1; A[j]:=i: end if od

Crossrefs

Cf. A003415, A007850.

Sequence in context: A214605 A186398 A124207 * A362811 A363681 A260923

Adjacent sequences: A189938 A189939 A189940 * A189942 A189943 A189944

Keyword

nonn

Author

Giorgio Balzarotti, May 01 2011

Status

approved