A053233 Numbers n such that A053230(n) = 2.

3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 33, 34, 35, 36, 37, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 69, 70, 71, 72, 73, 76, 77, 78, 79, 80, 81, 82, 83, 85

Offset

1,1

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Maple

with(numtheory): f := [seq( `if`((sigma(i+1) > sigma(i)), i, print( )), i=1..5000)];
seq( `if`(f[i+1] - f[i] = 2, i, print( )), i=1..100);

Mathematica

Position[Differences@ Select[Range[170], Less @@ DivisorSigma[1, # + {0, 1}] &], 2][[All, 1]] (* Michael De Vlieger, Nov 19 2019 *)

Prog

(Haskell)
import Data.List (elemIndices)
a053233 n = a053233_list !! (n-1)
a053233_list = map (+ 1) $ elemIndices 2 a053230_list
-- Reinhard Zumkeller, May 07 2012

Crossrefs

Cf. A000203, A053224, A053230, A053231, A053232, A053234, A053235, A053236, A053237.

Sequence in context: A062983 A081311 A366935 * A121818 A179005 A026505

Adjacent sequences: A053230 A053231 A053232 * A053234 A053235 A053236

Keyword

nonn

Author

Asher Auel, Jan 10 2000

Status

approved