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A057602 a(1)=2, a(n+1) is the smallest integer > a(n) such that the smallest prime factor of a(n+1) is the largest prime factor of a(n). 3
2, 4, 6, 9, 15, 25, 35, 49, 77, 121, 143, 169, 221, 289, 323, 361, 437, 529, 667, 841, 899, 961, 1147, 1369, 1517, 1681, 1763, 1849, 2021, 2209, 2491, 2809, 3127, 3481, 3599, 3721, 4087, 4489, 4757, 5041, 5183, 5329, 5767, 6241, 6557, 6889, 7387, 7921 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Even numbered terms are squares of successive primes. Odd numbered terms are the product of two successive primes and are the square root of the product of the previous term and the next term - Jud McCranie, Oct 07 2000
MATHEMATICA
Module[{nn=30, pr, ev, od}, pr=Prime[Range[nn]]; ev=pr^2; od=Times @@@ Partition[ pr, 2, 1]; Join[{2}, Riffle[ev, od]]] (* Harvey P. Dale, Mar 02 2015 *)
CROSSREFS
Cf. A000040.
Sequence in context: A266648 A076922 A157679 * A171646 A074677 A006498
KEYWORD
nonn
AUTHOR
G. L. Honaker, Jr., Oct 07 2000
EXTENSIONS
Additional terms from Jud McCranie, Oct 07 2000
STATUS
approved

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Last modified May 24 12:09 EDT 2024. Contains 372773 sequences. (Running on oeis4.)