A080720 - OEIS

A080720

a(0) = 5; 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".

5, 7, 8, 10, 11, 12, 13, 15, 18, 19, 21, 24, 27, 30, 31, 33, 34, 35, 36, 39, 40, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 54, 55, 57, 60, 63, 66, 67, 68, 69, 72, 73, 75, 78, 81, 84, 87, 90, 93, 96, 99, 102, 103, 104, 105, 108, 109, 111, 112, 113, 114, 115, 116, 117, 118, 119

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

OFFSET

0,1

LINKS

Table of n, a(n) for n=0..65.

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+4).

PROG

(PARI) {a=5; m=[5]; for(n=1, 66, 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: A309277 A180241 A047479 * A189034 A112250 A192067

Adjacent sequences: A080717 A080718 A080719 * A080721 A080722 A080723

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Mar 05 2003

EXTENSIONS

More terms and PARI code from Klaus Brockhaus, Mar 07 2003

STATUS

approved