A202342 Numbers occurring exactly twice in Hofstadter H-sequence A005374.

1, 4, 5, 7, 10, 13, 14, 17, 18, 20, 23, 24, 26, 29, 32, 33, 35, 38, 41, 42, 45, 46, 48, 51, 54, 55, 58, 59, 61, 64, 65, 67, 70, 73, 74, 77, 78, 80, 83, 84, 86, 89, 92, 93, 95, 98, 101, 102, 105, 106, 108, 111, 112, 114, 117, 120, 121, 123, 126, 129, 130, 133

Offset

1,2

Comments

A202340(a(n)) = 2.

Links

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

Larry Ericksen and Peter G. Anderson, Patterns in differences between rows in k-Zeckendorf arrays, The Fibonacci Quarterly, Vol. 50, No. 1 (February 2012), pp. 11-18.

Eric Weisstein's World of Mathematics, Hofstadter H-Sequence.

Wikipedia, Hofstadter sequence

Index entries for Hofstadter-type sequences

Formula

a(n) = A005374(A136496(n)). - Alan Michael Gómez Calderón, Dec 22 2024

a(n) = A136495(A136495(n)). - Alan Michael Gómez Calderón, Jan 06 2025

Prog

(Haskell)
import Data.List (elemIndices)
a202342 n = a202342_list !! (n-1)
a202342_list = elemIndices 2 a202340_list

Crossrefs

Cf. A005374, A202340, A136495, A136496, A202341 (complement).

Sequence in context: A269861 A187479 A013947 * A234141 A093517 A248858

Adjacent sequences: A202339 A202340 A202341 * A202343 A202344 A202345

Keyword

nonn

Author

Reinhard Zumkeller, Dec 17 2011

Status

approved