The OEIS is supported by the many generous donors to the OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A057167 Term in Recamán's sequence A005132 where n appears for first time, or -1 if n never appears. 21
 0, 1, 4, 2, 131, 129, 3, 5, 16, 14, 12, 10, 8, 6, 31, 29, 27, 25, 23, 99734, 7, 9, 11, 13, 15, 17, 64, 62, 60, 58, 56, 54, 52, 50, 48, 46, 44, 42, 40, 38, 111, 22, 20, 18, 28, 30, 32, 222, 220, 218, 216, 214, 212, 210, 208, 206, 204, 202, 200, 198, 196 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS T. D. Noe, Table of n, a(n) for n=0..1642 (taking a(1355) from A064227) Nick Hobson, Python program for this sequence C. L. Mallows, Plot (jpeg) of first 10000 terms of A005132 C. L. Mallows, Plot (postscript) of first 10000 terms of A005132 N. J. A. Sloane, My favorite integer sequences, in Sequences and their Applications (Proceedings of SETA '98). N. J. A. Sloane, FORTRAN program for A005132, A057167, A064227, A064228 MAPLE w := array(1..10000); for j from 1 to 100 do l := 0; for k from 1 to nops(a) do if a[k] = j then l := k; exit; fi; od: w[j] := l; od: s := [seq(w[j], j=1..100)]; # where a is an array formed from sequence A005132 MATHEMATICA A005132 = {0}; Do[If[(r = Last[A005132] - n) <= 0 || MemberQ[ A005132, r], r = r + 2n]; AppendTo[ A005132, r], {n, 1, 10^5}]; a[n_] := If[p = Position[ A005132, n]; p == {}, 0, p[[1, 1]] - 1]; Table[a[n], {n, 1, 60}] (* Jean-François Alcover, Jul 18 2012 *) PROG (PARI) first(n) = my(a=vector(n), r=); while(#Set(a)= 0 and t not in A005132set else an + n         A005132set.add(an)         inv[an] = n         while y in inv: yield inv[y]; y += 1 print(list(islice(agen(), 61))) # Michael S. Branicky, Jul 12 2022 CROSSREFS Cf. A005132, A057165, A057166. Cf. also A187943, A187922. Sequence in context: A201228 A010319 A266069 * A355646 A096683 A158903 Adjacent sequences:  A057164 A057165 A057166 * A057168 A057169 A057170 KEYWORD nonn,easy,nice,look AUTHOR N. J. A. Sloane, Sep 14 2000 EXTENSIONS I conjecture a(n) is never -1 - but see A064227, A064228. a(0)=0 added and escape clause value changed to -1 by N. J. A. Sloane, May 01 2020 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 September 27 13:46 EDT 2022. Contains 357062 sequences. (Running on oeis4.)