The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A253887 Row index of n in A191450: a(3n) = 2n, a(3n+1) = 2n+1, a(3n+2) = a(n+1). 13
 1, 1, 2, 3, 1, 4, 5, 2, 6, 7, 3, 8, 9, 1, 10, 11, 4, 12, 13, 5, 14, 15, 2, 16, 17, 6, 18, 19, 7, 20, 21, 3, 22, 23, 8, 24, 25, 9, 26, 27, 1, 28, 29, 10, 30, 31, 11, 32, 33, 4, 34, 35, 12, 36, 37, 13, 38, 39, 5, 40, 41, 14, 42, 43, 15, 44, 45, 2, 46, 47, 16, 48, 49, 17, 50, 51, 6, 52, 53, 18, 54, 55, 19, 56, 57, 7 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) gives the row index of n in square array A191450, or equally, the column index of n in A254051. LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 FORMULA a(3n) = 2n, a(3n+1) = 2n+1, a(3n+2) = a(n+1). a(n) = A126760(2n-1). a(n) = A249746(A003602(A064216(n))). - Antti Karttunen, Feb 04 2015 PROG (Scheme, with memoization-macro definec) (definec (A253887 n) (if (= 2 (modulo n 3)) (A253887 (/ (+ 1 n) 3)) (inv_for_A032766 n))) (define (inv_for_A032766 n) (+ (* 2 (floor->exact (/ n 3))) (modulo n 3))) (Python) def a(n): if n%3==0: return 2*n//3 elif n%3==1: return 2*(n - 1)//3 + 1 else: return a((n - 2)//3 + 1) print([a(n) for n in range(1, 101)]) # Indranil Ghosh, Jun 06 2017 CROSSREFS Odd bisection of A126760. Cf. A254046 (the corresponding column index). Cf. A003602, A032766, A064216, A253786, A253893, A249746. Cf. A191450, A254051, A254047, A254052, A254104. Sequence in context: A256946 A285715 A328456 * A026370 A078446 A357241 Adjacent sequences: A253884 A253885 A253886 * A253888 A253889 A253890 KEYWORD nonn AUTHOR Antti Karttunen, Jan 22 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified July 20 13:32 EDT 2024. Contains 374445 sequences. (Running on oeis4.)