A064788 - OEIS

A064788

Inverse permutation to A060736.

1, 2, 5, 3, 4, 8, 13, 9, 6, 7, 12, 18, 25, 19, 14, 10, 11, 17, 24, 32, 41, 33, 26, 20, 15, 16, 23, 31, 40, 50, 61, 51, 42, 34, 27, 21, 22, 30, 39, 49, 60, 72, 85, 73, 62, 52, 43, 35, 28, 29, 38, 48, 59, 71, 84, 98, 113, 99, 86, 74, 63, 53, 44, 36, 37, 47, 58, 70, 83, 97, 112

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..71.

Boris Putievskiy, Transformations Integer Sequences And Pairing Functions, arXiv:1212.2732 [math.CO], 2012.

Eric Weisstein's MathWorld, Pairing functions

Index entries for sequences that are permutations of the natural numbers

FORMULA

a(n) = (i+j-1)*(i+j-2)/2+j, where i=min(t; t^2-n+1), j=min(t; n-(t-1)^2), t=floor(sqrt(n-1))+1. - Boris Putievskiy, Dec 24 2012

PROG

(PARI) A064788(n)={my(t=sqrtint(n-1)+1); A000217(min(t, t^2-n+1)-2+n=min(t, n-(t-1)^2))+n} \\ recall: A000217(n)=(n+1)*n/2 \\ M. F. Hasler, Jan 13 2013

CROSSREFS

Cf. A064790, A194280.

Sequence in context: A245815 A105108 A118460 * A099521 A331373 A120238

Adjacent sequences: A064785 A064786 A064787 * A064789 A064790 A064791

KEYWORD

easy,nonn

AUTHOR

N. J. A. Sloane, Oct 20 2001

EXTENSIONS

More terms from David Wasserman, Jan 15 2002

STATUS

approved