A053235 - OEIS

%I #14 Oct 27 2023 22:00:45

%S 158,202,263,350,387,476,567,582,701,790,879,894,926,999,1103,1236,

%T 1282,1403,1418,1501,1523,1646,1661,1737,1831,1847,1953,2059,2074,

%U 2149,2185,2237,2265,2370,2505,2563,2683,2729,2873,2894,2909,3032,3107,3127

%N Numbers n such that A053230(n) = 3.

%H Reinhard Zumkeller, <a href="/A053235/b053235.txt">Table of n, a(n) for n = 1..10000</a>

%p with(numtheory): f := [seq( `if`((sigma(i+1) > sigma(i)),i,print( )), i=1..5000)];

%p seq( `if`(f[i+1] - f[i] = 3,i,print( )), i=1..1000);

%t Position[Differences@ Select[Range[10^4], Less @@ DivisorSigma[1, # + {0, 1}] &], 3][[All, 1]] (* _Michael De Vlieger_, Nov 19 2019 *)

%o (Haskell)

%o import Data.List (elemIndices)

%o a053235 n = a053235_list !! (n-1)

%o a053235_list = map (+ 1) $ elemIndices 3 a053230_list

%o -- _Reinhard Zumkeller_, May 07 2012

%Y Cf. A000203, A053224, A053230, A053231, A053232, A053233, A053234, A053236, A053237.

%K nonn

%O 1,1

%A _Asher Auel_, Jan 10 2000