A276786 a(1) = 1; subsequent terms are defined by the rule that if m is present so are 2m+1 and 3m+1; repeated terms are included; final list is sorted.

1, 3, 4, 7, 9, 10, 13, 15, 19, 21, 22, 27, 28, 31, 31, 39, 40, 43, 45, 46, 55, 57, 58, 63, 63, 64, 67, 79, 81, 82, 85, 87, 91, 93, 94, 94, 111, 115, 117, 118, 121, 127, 127, 129, 130, 135, 136, 139, 159, 163, 165, 166, 171, 172, 175, 175, 183, 187, 189, 189, 190, 190, 193, 202, 223, 231, 235, 237, 238

Offset: 1

Author

N. J. A. Sloane, Oct 06 2016

Keywords

• nonn

Comments

31 is the first number to appear twice. This is a multi-set version of the Klarner-Rado sequence A002977.

20479 is the first number to appear three times. - Rémy Sigrist, Dec 19 2016

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..29993 [Terms up to 500000]
• J. C. Lagarias, Erdős, Klarner and the 3x + 1 Problem, Amer. Math. Monthly 123 (No. 8, 2016), 753-776. See S# on page 756.
• Rémy Sigrist, C99 program for A276786

Crossrefs

Cf. A002977. See A276787 for repeated terms.

Programs

Maple

KR:=proc(lis) local i,j,t1,t2,t3;
t1:=lis; t2:=nops(lis); t3:=[];
for i from 1 to t2 do j:=t1[i];
t3:=[op(t3),2*j+1,3*j+1]; od: sort(t3); end;
t:=[1]; b:=[1];
for n from 1 to 10 do
t:=KR(t); b:=[op(b),op(t)]; b:=sort(b);
od: b;