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A189941 Numbers n such that n''' = n''+ 1 where n'' and n''' are respectively the second and the third arithmetic derivative of n. 1
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 (list; graph; refs; listen; history; text; internal format)
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 * A260923 A151701 A258276

Adjacent sequences:  A189938 A189939 A189940 * A189942 A189943 A189944

KEYWORD

nonn

AUTHOR

Giorgio Balzarotti, May 01 2011

STATUS

approved

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Last modified August 12 04:57 EDT 2020. Contains 336436 sequences. (Running on oeis4.)