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Numbers n such that A053230(n) = 4.
8

%I #13 Oct 27 2023 22:00:45

%S 23,54,59,84,114,138,149,172,177,232,257,281,293,311,355,392,417,422,

%T 434,445,481,506,561,596,601,644,656,686,715,745,763,775,798,809,853,

%U 864,944,955,979,984,1013,1018,1061,1072,1140,1164,1187,1192,1222,1227

%N Numbers n such that A053230(n) = 4.

%H Reinhard Zumkeller, <a href="/A053236/b053236.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..8000)];

%p seq( `if`(f[i+1] - f[i] = 4,i,print( )), i=1..3000);

%o (Haskell)

%o import Data.List (elemIndices)

%o a053236 n = a053236_list !! (n-1)

%o a053236_list = map (+ 1) $ elemIndices 4 a053230_list

%o -- _Reinhard Zumkeller_, May 07 2012

%Y Cf. A000203, A053224, A053230, A053231, A053232, A053233, A053234, A053235, A053237.

%K nonn

%O 1,1

%A _Asher Auel_, Jan 10 2000