A064568 n-th term in Recamán's sequence A005132 is divisible by n.

1, 3, 11, 21, 39, 76, 248, 844, 1520, 2752, 9317, 17223, 31221, 57071, 99741, 589932, 58056875, 101769229, 302890748, 511561220, 904036924, 39488697700, 325374626148, 535755688021, 1404720439053, 3883018238329, 6283167591179, 16166305650060, 25735985498861, 40806937801472

Offset: 1

Author

N. J. A. Sloane, Oct 16 2001

Keywords

• nonn
• more

Comments

No more terms < 4.61*10^11. - Jud McCranie, Dec 29 2019

No more terms < 6.46*10^13. - James Ewens, Sep 27 2024

Examples

			A005132(21) = 63, 63 is divisible by 21, so 21 is in the sequence.
		

Links

• Index entries for sequences related to Recamán's sequence

Crossrefs

Cf. A005132, A064569.

Programs

Mathematica

With[{s = Nest[Append[#1, If[And[#3 > 0, FreeQ[#1, #3]], #3, #1[[-1]] + #2]] & @@ {#1, #2, #1[[-1]] - #2} & @@ {#, Length@ #} &, {0}, 10^5]}, Reap[Do[If[Mod[s[[i]], i] == 0, Sow[i]], {i, Length@ s - 1}]][[-1, -1]]] (* Michael De Vlieger, Dec 29 2019 *)

Extensions

Offset changed, a(1), a(22)-a(23) from Jud McCranie, Dec 29 2019

a(24)-a(30) from James Ewens, Sep 27 2024