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A376358 Positions of numbers in A007961 that end in 1.

%I A376358 #7 Sep 28 2024 12:59:22
%S A376358 1,5,10,14,17,21,26,30,35,37,41,46,50,54,59,63,65,69,74,78,82,86,91,
%T A376358 95,98,101,105,110,114,117,122,126,131,135,138,142,145,149,154,158,
%U A376358 161,165,170,174,179,183,186,190,195,197,201,206,210,213,217,222,226
%N A376358 Positions of numbers in A007961 that end in 1.
%C A376358 Every positive integer is in exactly one of these sequences: A376358, this sequence, A376359, or A376360.
%C A376358 Conjecture: {a(n+1) - a(n) : n >= 1} = {2,3,4,5,6,7}. (See related conjectures at A376357, A376359, and A376360.)
%t A376358 a[n_, poly_] := FromDigits[FoldList[{Mod[#[[1]], #2], Quotient[#[[1]], #2]} &, {n, 0}, Reverse[Map[(poly - 2)  #  (# - 1)/2 + # &,
%t A376358 Range[Floor[Sqrt[2  n]]]]]][[All, 2]]]
%t A376358 t4 = Map[a[#, 4] &, Range[200]];  (* A007961 *)
%t A376358 m = Mod[t4, 10];
%t A376358 Table[Flatten[Position[m, r]], {r, 0, 2}]
%t A376358 p0 = Flatten[Position[m, 0]]  (* A376357 *)
%t A376358 p1 = Flatten[Position[m, 1]]  (* this sequence *)
%t A376358 p2 = Flatten[Position[m, 2]]  (* A376359 *)
%t A376358 p3 = Flatten[Position[m, 3]]  (* A376360 *)
%t A376358 (* _Peter J. C. Moses_, Sep 20 2024 *)
%Y A376358 Cf. A007961, A376354, A376357, A376359, A376360.
%K A376358 nonn,base
%O A376358 1,2
%A A376358 _Clark Kimberling_, Sep 25 2024