A352544 - OEIS

A352544

a(n) = n/2 if n is even, otherwise n + A004186(n), where A004186 = arrange digits in decreasing order.

0, 2, 1, 6, 2, 10, 3, 14, 4, 18, 5, 22, 6, 44, 7, 66, 8, 88, 9, 110, 10, 42, 11, 55, 12, 77, 13, 99, 14, 121, 15, 62, 16, 66, 17, 88, 18, 110, 19, 132, 20, 82, 21, 86, 22, 99, 23, 121, 24, 143, 25, 102, 26, 106, 27, 110, 28, 132, 29, 154, 30, 122, 31, 126, 32, 130, 33, 143, 34, 165, 35, 142, 36, 146, 37, 150, 38, 154, 39, 176, 40, 162, 41, 166, 42, 170, 43, 174, 44, 187, 45

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OFFSET

0,2

COMMENTS

A variant of the Collatz (3x+1) map A006370. See A352540 - A352543 for more about iterations of this map.

LINKS

Table of n, a(n) for n=0..90.

Eric Angelini, Divide by 2 or add the biggest anagram, math-fun discussion list, Mar 20 2022

PROG

(PARI) apply( {A352544(n)=if(n%2, n+A004186(n), n\2)}, [0..90]) \\ with A004186(n)=fromdigits(vecsort(digits(n), , 4))

CROSSREFS

Cf. A004186.

Coincides with A064680 (half if even, double if odd) for n < 13.

Cf. A352540 (initial values with infinite orbit under A352544), A352541 (number of iterations of A352544 to reach a value for the second time), A352542 (orbit of 89 under A352544), A352543 (numbers that end in a loop of length > 3 under A352544), A352545 (representatives of loops of length > 3).

Sequence in context: A368241 A099304 A064680 * A363596 A354280 A239148

Adjacent sequences: A352541 A352542 A352543 * A352545 A352546 A352547

KEYWORD

nonn,base

AUTHOR

Eric Angelini and M. F. Hasler, Mar 20 2022

STATUS

approved