

A271530


a(1) = 1; thereafter a(n) is the product of all 0 < m < n for which n == a(m) (mod m).


2



1, 1, 2, 1, 24, 1, 12, 3, 40, 1, 480, 7, 432, 15, 28, 13, 24, 11, 40320, 3, 1520, 9, 120, 85, 48, 21, 16, 345, 1452971520, 1, 8553600, 3, 56, 5, 44544, 1, 1161216, 3, 340, 13167, 155040, 13, 130636800, 15, 4736, 1, 36167040, 1075, 66960, 63, 40480, 1, 27456
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OFFSET

1,3


LINKS

Peter Kagey, Table of n, a(n) for n = 1..10000


EXAMPLE

a(1) = 1 by definition.
a(2) = 1, because 2 == a(1) (mod 1);
a(3) = 2, because 3 == a(1) (mod 1), and 3 == a(2) (mod 2): 1 * 2 = 2;
a(4) = 1, because 4 == a(1) (mod 1);
a(5) = 24, because 5 == k (mod k) for 0 < k < 5: 1 * 2 * 3 * 4 = 24.


MATHEMATICA

a = {1}; Do[AppendTo[a, Times @@ Flatten@ Position[MapIndexed[Mod[n, First@ #2] == Mod[#1, First@ #2] &, a], True]], {n, 2, 53}]; a (* Michael De Vlieger, Apr 09 2016 *)


CROSSREFS

Cf. A269423, A271531.
Sequence in context: A279308 A345262 A108778 * A062763 A243147 A261407
Adjacent sequences: A271527 A271528 A271529 * A271531 A271532 A271533


KEYWORD

nonn


AUTHOR

Peter Kagey, Apr 09 2016


STATUS

approved



