A062321 - OEIS

A062321

a(1) = 1; a(n) = gcd {n*(n+1), a(n-1) * (a(n-1) + 1)} for n > 1.

1, 2, 6, 2, 6, 42, 14, 6, 6, 2, 6, 6, 14, 210, 30, 2, 6, 6, 2, 6, 42, 2, 6, 6, 2, 6, 42, 14, 30, 930, 62, 6, 6, 14, 210, 6, 2, 6, 6, 2, 6, 42, 86, 6, 6, 2, 6, 42, 14, 30, 6, 2, 6, 6, 14, 42, 6, 2, 6, 6, 2, 6, 42, 2, 6, 6, 2, 6, 42, 14, 6, 6, 2, 6, 6, 14, 42, 6, 2, 6, 6, 2, 6, 42, 86, 7482

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

EXAMPLE

a(31) = gcd(31 * 32, a(30) * (a(30) + 1)) = gcd(31*32, 930*931) = 62

MATHEMATICA

RecurrenceTable[{a[1]==1, a[n]==GCD[n(n+1), a[n-1](a[n-1]+1)]}, a, {n, 90}] (* Harvey P. Dale, Dec 21 2011 *)

PROG

(PARI) { for (n=1, 1000, if (n>1, a=gcd(n*(n + 1), a*(a + 1)), a=1); write("b062321.txt", n, " ", a) ) } \\ Harry J. Smith, Aug 04 2009

CROSSREFS