A360905 Starts of run of 3 consecutive integers that are all terms of A360902.

7939375, 12799375, 20410623, 30466287, 56661199, 83365119, 105146991, 197479375, 235838223, 259360623, 293380623, 555499375, 657880623, 691579375, 871374591, 871720623, 953280495, 975079375, 996393391, 1032100623, 1047979375, 1096579375, 1348000623, 1355419375

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..300

Example

7939375 is a term since A034444(7939375) = A005361(7939375) = 4, A034444(7939376) = A005361(7939376) = 4, and A034444(7939377) = A005361(7939377) = 4.

Mathematica

q[n_] := Module[{e = FactorInteger[n][[;; , 2]]}, Times @@ e == 2^Length[e]]; q[1] = True; seq[kmax_] := Module[{tri = q /@ Range[3], s = {}, k = 4}, While[k < kmax, If[And @@ tri, AppendTo[s, k - 3]]; tri = Join[Rest[tri], {q[k]}]; k++]; s]; seq[10^7]

Prog

(PARI) is(k) = {my(e = factor(k)[, 2]); prod(i = 1, #e, e[i]) == 2^#e; }
lista(kmax) = {my(tri = vector(3, i, is(i)), k = 4); while(k < kmax, if(vecsum(tri) == 3, print1(k-3, ", ")); tri = concat(vecextract(tri, "^1"), is(k)); k++); }

Crossrefs

Subsequence of A360902 and A360903.

Cf. A005361, A034444.

Sequence in context: A210275 A346029 A237338 * A233797 A203504 A233803

Adjacent sequences: A360902 A360903 A360904 * A360906 A360907 A360908

Keyword

nonn

Author

Amiram Eldar, Feb 25 2023

Status

approved