A287612 Ulam numbers k such that 4*k is also an Ulam number.

1, 2, 4, 18, 114, 131, 180, 258, 324, 412, 431, 605, 646, 864, 1037, 1081, 1101, 1167, 1296, 1313, 1404, 1470, 1765, 1856, 1858, 1900, 1944, 2032, 2117, 2327, 2572, 2630, 2635, 2674, 2787, 2809, 2814, 2897, 3068, 3214, 3219, 3261, 3393, 3451, 3591, 3622, 3630

Offset

1,2

Links

Table of n, a(n) for n=1..47.

Mathematica

(* First run one of the programs for A002858 to populate the ulams list *) A287612 = ulams; curr = 1; While[curr < Length[ulams] + 1, A287612[[curr]] = ulams[[curr]] * Boole[MemberQ[ulams, 4ulams[[curr]]]]; curr++]; DeleteCases[A287612, 0] (* Alonso del Arte, May 28 2017 *)

Crossrefs

Cf. A002858, A068791, A285885.

Sequence in context: A067647 A208358 A213793 * A308755 A318394 A228933

Adjacent sequences: A287609 A287610 A287611 * A287613 A287614 A287615

Keyword

nonn

Author

Enrique Navarrete, May 27 2017

Status

approved