A080712 - OEIS

A080712

a(0) = 4; 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".

4, 5, 7, 8, 9, 12, 13, 15, 18, 21, 22, 23, 24, 27, 28, 30, 31, 32, 33, 34, 35, 36, 39, 42, 45, 46, 47, 48, 51, 52, 54, 57, 60, 63, 66, 69, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 84, 87, 90, 91, 92, 93, 96, 97, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

LINKS

Table of n, a(n) for n=0..66.

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+3).

PROG

(PARI) {a=4; m=[4]; for(n=1, 67, 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, A080711, A080710.

Sequence in context: A266267 A189477 A047494 * A005048 A119642 A276705

Adjacent sequences: A080709 A080710 A080711 * A080713 A080714 A080715

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