A376359 Positions of numbers in A007961 that end in 2.

2, 6, 11, 15, 18, 22, 27, 31, 38, 42, 47, 51, 55, 60, 66, 70, 75, 79, 83, 87, 92, 96, 99, 102, 106, 111, 115, 118, 123, 127, 132, 136, 139, 143, 146, 150, 155, 159, 162, 166, 171, 175, 180, 184, 187, 191, 198, 202, 207, 211, 214, 218, 223, 227, 231, 236, 240

Offset

1,1

Comments

Every positive integer is in exactly one of these sequences: A376357, A376358, this sequence, or A376360.

Conjecture: {a(n+1) - a(n) : n >= 1} = {3,4,5,6,7,8,9,10}. (See related conjectures at A376357, A376358, and A376360.)

Links

Table of n, a(n) for n=1..57.

Mathematica

a[n_, poly_] := FromDigits[FoldList[{Mod[#[[1]], #2], Quotient[#[[1]], #2]} &, {n, 0}, Reverse[Map[(poly - 2)  #  (# - 1)/2 + # &,
Range[Floor[Sqrt[2  n]]]]]][[All, 2]]]
t4 = Map[a[#, 4] &, Range[200]];  (* A007961 *)
m = Mod[t4, 10];
Table[Flatten[Position[m, r]], {r, 0, 2}]
p0 = Flatten[Position[m, 0]]  (* A376357 *)
p1 = Flatten[Position[m, 1]]  (* A376359 *)
p2 = Flatten[Position[m, 2]]  (* this sequence *)
p3 = Flatten[Position[m, 3]]  (* A376360 *)
(* Peter J. C. Moses, Sep 20 2024 *)

Crossrefs

Cf. A007961, A376354, A376357, A376358, A376360.

Sequence in context: A138327 A057244 A241672 * A377287 A035487 A299637

Adjacent sequences: A376356 A376357 A376358 * A376360 A376361 A376362

Keyword

nonn,base

Author

Clark Kimberling, Sep 25 2024

Status

approved