A080711 a(0) = 2; for n>0, a(n) is taken to be the smallest positive integer greater than a(n-1) which is consistent with the condition "n is a member of the sequence if and only if a(n) is a multiple of 3".

2, 4, 6, 7, 9, 10, 12, 15, 16, 18, 21, 22, 24, 25, 26, 27, 30, 31, 33, 34, 35, 36, 39, 40, 42, 45, 48, 51, 52, 53, 54, 57, 58, 60, 63, 66, 69, 70, 71, 72, 75, 76, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 90, 93, 96, 97, 98, 99, 102, 103, 105, 106, 107, 108, 109, 110, 111, 112

Offset

0,1

Links

Table of n, a(n) for n=0..67.

B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence, J. Integer Seqs., Vol. 6 (2003), #03.2.2.

B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence (math.NT/0305308)

Index entries for sequences of the a(a(n)) = 2n family

Formula

a(a(n)) = 3*(n+2).

Prog

(PARI) {a=2; m=[2]; for(n=1, 68, print1(a, ", "); a=a+1; if(m[1]==n, while(a%3>0, a++); m=if(length(m)==1, [], vecextract(m, "2..")), if(a%3==0, a++)); m=concat(m, a))}

Crossrefs

Cf. A079000, A003605, A079253, A080710, A080712.

Sequence in context: A213733 A218608 A288475 * A022301 A050099 A184333

Adjacent sequences: A080708 A080709 A080710 * A080712 A080713 A080714

Keyword

nonn,easy

Author

N. J. A. Sloane, Mar 05 2003

Extensions

More terms and PARI code from Klaus Brockhaus, Mar 06 2003

Status

approved