cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A260729 Iterates of A234742, starting from value a(0) = 29, with a(1) = A234742(a(0)), a(2) = A234742(a(1)), etc.

Original entry on oeis.org

29, 33, 93, 217, 341, 961, 2821, 7409, 8973, 53625, 94325, 225169, 470517, 1349089, 4076589, 22862205, 40165377, 506257425, 918577233, 1042701969, 5347778553, 76822655445, 242180261569, 243151045949, 835744242025, 1398202164821, 7718585207745, 17886399120625, 36628781776125, 140199249091321, 579641775855025, 3110633457224293, 9887055813390673
Offset: 0

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Author

Antti Karttunen, Aug 04 2015

Keywords

Comments

The sequence reaches its fixed point at a(141) = after which the sequence stays constant, a(142) = a(143) = a(144), etc.

Crossrefs

Cf. also A244323, A260735, A260441 for iterations starting from other values.

Programs

  • PARI
    allocatemem((2^29));
    A234742(n) = factorback(subst(lift(factor(Mod(1, 2)*Pol(binary(n)))), x, 2)); \\ After M. F. Hasler's Feb 18 2014 code.
    iterates_of_A234742(start, filename) = {my(n=start, prev=-1, prevprev=-1, i=0); until((n==prevprev), write(filename, i, " ", n); prevprev = prev; prev = n; n = A234742(n); i++)} \\ Computes b-file up to the second occurrence of the fixed point.
    iterates_of_A234742(29, "b260729.txt")
    
  • Scheme
    ;; With memoizing macro definec.
    (definec (A260729 n) (if (zero? n) 29 (A234742 (A260729 (- n 1)))))

Formula

a(0) = 29; for n >= 1, a(n) = A234742(a(n-1)).