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A087552 a(1) = 1, then the smallest prime divisor of A065447(n) not included earlier. 0
1, 2, 11, 5, 3, 29, 101, 113, 41, 271, 7, 13, 239, 613, 73, 137, 37, 8291, 9091, 157637, 313, 21649, 9901, 2733970560857, 53, 79, 229, 4649, 31, 13001, 17, 19, 6529, 664193, 6781, 52579, 1111111111111111111 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Conjecture: Every prime is a member and this is a rearrangement of the noncomposite numbers.

Proof of conjecture: primes 2=a(1) and 5=a(3) are terms, while any other prime divides infinitely many numbers of the form A002275([(n+1)/2]) = (10^[(n+1)/2]-1)/9, which in turn divide A065447(n). Thus every prime will sooner or later appear as a(n). - Max Alekseyev, Jul 03 2019

LINKS

Table of n, a(n) for n=1..37.

EXAMPLE

a(6) = 29; smallest prime divisor of 100111000011111000000 not included earlier is 29. The prime divisors are 2, 3, 5, 29, 37, 97 and 106872959.

CROSSREFS

Sequence in context: A257112 A077272 A009301 * A124688 A158616 A127821

Adjacent sequences:  A087549 A087550 A087551 * A087553 A087554 A087555

KEYWORD

base,more,nonn

AUTHOR

Amarnath Murthy, Sep 13 2003

EXTENSIONS

More terms from David Wasserman, Jun 06 2005

Offset corrected by Max Alekseyev, Jul 03 2019

STATUS

approved

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Last modified October 22 17:39 EDT 2019. Contains 328319 sequences. (Running on oeis4.)