A118362 a(1)=1; for n>1, a(n) = "n AND a(n-1)" if that number is positive and not already in the sequence, otherwise a(n) = "n OR a(n-1)".

1, 3, 3, 7, 5, 4, 7, 15, 9, 8, 11, 15, 13, 12, 15, 31, 17, 16, 19, 23, 21, 20, 23, 31, 25, 24, 27, 31, 29, 28, 31, 63, 33, 32, 35, 39, 37, 36, 39, 47, 41, 40, 43, 47, 45, 44, 47, 63, 49, 48, 51, 55, 53, 52, 55, 63, 57, 56, 59, 63, 61, 60, 63, 127, 65, 64, 67, 71, 69, 68, 71, 79

Offset: 1

Author

N. J. A. Sloane, May 17 2006

Keywords

• nonn
• easy

Comments

Here "AND" and "OR" refer to operations on the binary expansions of the argument.

Crossrefs

Cf. A005132.

Programs

PARI

A118362(maxn)= { local(a,aSet,aand,newa) ; a=[1] ; for(n=2,maxn, aSet=Set(a) ; aand=bitand(a[n-1],n) ; if( aand >0 && setsearch(aSet,aand) == 0, newa=aand, newa=bitor(a[n-1],n) ; ) ; a=concat(a,newa) ; print(newa) ; ) ; return(a) ; } print(A118362(80)) ; (Mathar)

Extensions

More terms from R. J. Mathar and Joshua Zucker, May 18 2006