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 A086762 A piecewise recurrence relation with a(2)=7 and for n>=2: if a(n) is prime, not 31, a(n+1) = A000265(3*a(n)+1); if a(n) is odd composite, not 1, a(n+1) = A000265(a(n)+1); if a(n) is even, a(n+1) = A000265(a(n)); if a(n) is 1 or 31, find the number S(n) of occurrences of 1 and 31 among a(2),a(3),...,a(n) and compute a(n+1) by the above rules as if a(n) were 2+S(n), unless 2+S(n)=31, in which case a(n+1)=47. 1
 7, 11, 17, 13, 5, 1, 5, 1, 1, 1, 3, 5, 1, 11, 17, 13, 5, 1, 1, 5, 1, 5, 1, 17, 13, 5, 1, 3, 5, 1, 5, 1, 7, 11, 17, 13, 5, 1, 1, 1, 13, 5, 1, 9, 5, 1, 29, 11, 17, 13, 5, 1, 5, 1, 11, 17, 13, 5, 1, 11, 17, 13, 5, 1, 35, 9, 5, 1, 3, 5, 1, 13, 5, 1, 13, 5, 1, 7, 11, 17, 13, 5, 1, 7, 11, 17, 13, 5, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS Note that if we treated 31 like the other primes, we would enter the infinite loop 31, 47, 71, 107, 161, 81, 41, 31. Are there any remaining infinite loops? LINKS PROG (PARI) pxp1(m) = { for(x=2, m, n=x; while(n > 1, if(isprime(n), n=n*3+1, if(n%2<>0, n++)); while(n%2==0, n/=2); print1(n", "); if(n==1 || n==31, break); ) ) } CROSSREFS Cf. A086763, A000265. Sequence in context: A022950 A293343 A131626 * A296305 A076045 A101618 Adjacent sequences:  A086759 A086760 A086761 * A086763 A086764 A086765 KEYWORD easy,nonn AUTHOR Cino Hilliard, Aug 02 2003 EXTENSIONS Edited by Sam Alexander, Jan 05 2005 STATUS approved

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Last modified January 23 19:45 EST 2020. Contains 331175 sequences. (Running on oeis4.)