

A080725


a(1) = 2; for n>1, a(n) is taken to be the smallest positive integer greater than a(n1) which is consistent with the condition "n is a member of the sequence if and only if a(n) == 1 mod 3".


0



2, 4, 5, 7, 10, 11, 13, 14, 15, 16, 19, 20, 22, 25, 28, 31, 32, 33, 34, 37, 38, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 52, 55, 58, 59, 60, 61, 64, 65, 67, 70, 73, 76, 79, 82, 85, 88, 91, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 106, 109, 112, 113, 114, 115, 118, 119, 121
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OFFSET

1,1


LINKS



FORMULA

a(a(n)) = 3*n+1, n >= 1.


PROG

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


CROSSREFS



KEYWORD

nonn,easy


AUTHOR



EXTENSIONS



STATUS

approved



