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

Author

Amiram Eldar, Feb 25 2023

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Subsequence of A360902 and A360903.

Cf. A005361, A034444.

Programs

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]

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++); }