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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A268861 Cubefree numbers n such that n + 1 is a perfect cube. 1
 7, 26, 63, 124, 215, 342, 511, 1330, 1727, 2196, 2743, 3374, 4095, 7999, 9260, 10647, 12166, 13823, 17575, 19682, 24388, 26999, 29790, 32767, 39303, 42874, 46655, 54871, 59318, 63999, 74087, 79506, 85183, 91124, 103822, 110591, 124999, 132650, 140607, 148876 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Intersection of A004709 and A068601. - Michel Marcus, Feb 15 2016 LINKS K. D. Bajpai, Table of n, a(n) for n = 1..400 EXAMPLE a(2) = 26 = 2 * 13 that is cubefree. 26 + 1 = 27 = 3^3 (perfect cube). a(4) = 124 = 2 * 2 * 31 that is cubefree. 124 + 1 = 125 = 5^3 (perfect cube). MAPLE cubefree:= proc(n) local t; max(seq(t[2], t=ifactors(n)[2])) <= 2 end proc: select(cubefree, [seq(i^3-1, i=2..100)]); # Robert Israel, Mar 03 2016 MATHEMATICA Select[Range[150000], FreeQ[FactorInteger[#], {_, k_ /; k > 2}] && IntegerQ[CubeRoot[# + 1]] &] Select[Range[2, 70]^3, Max[FactorInteger[#-1][[All, 2]]]<3&]-1 (* Harvey P. Dale, Oct 11 2021 *) PROG (PARI) for(n=1, 1e5, f = factor(n)[, 2]; if((#f == 0) || vecmax(f) < 3, if(ispower(n + 1, 3), print1(n, ", ")))); CROSSREFS Cf. A004709, A068601, A121628, A221793, A268752. Sequence in context: A135300 A024001 A068601 * A221793 A299282 A269700 Adjacent sequences: A268858 A268859 A268860 * A268862 A268863 A268864 KEYWORD nonn AUTHOR K. D. Bajpai, Feb 14 2016 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 April 13 15:44 EDT 2024. Contains 371644 sequences. (Running on oeis4.)