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A320629 Products of odd primes of nonprime index. 5
1, 7, 13, 19, 23, 29, 37, 43, 47, 49, 53, 61, 71, 73, 79, 89, 91, 97, 101, 103, 107, 113, 131, 133, 137, 139, 149, 151, 161, 163, 167, 169, 173, 181, 193, 197, 199, 203, 223, 227, 229, 233, 239, 247, 251, 257, 259, 263, 269, 271, 281, 293, 299, 301, 307, 311 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The index of a prime number n is the number m such that n is the m-th prime.

LINKS

Table of n, a(n) for n=1..56.

EXAMPLE

The sequence of terms begins:

    1 = 1

    7 = prime(4)

   13 = prime(6)

   19 = prime(8)

   23 = prime(9)

   29 = prime(10)

   37 = prime(12)

   43 = prime(14)

   47 = prime(15)

   49 = prime(4)^2

   53 = prime(16)

   61 = prime(18)

   71 = prime(20)

   73 = prime(21)

   79 = prime(22)

   89 = prime(24)

   91 = prime(4)*prime(6)

   97 = prime(25)

  101 = prime(26)

  103 = prime(27)

  107 = prime(28)

  113 = prime(30)

  131 = prime(32)

  133 = prime(4)*prime(8)

  137 = prime(33)

  139 = prime(34)

  149 = prime(35)

  151 = prime(36)

  161 = prime(4)*prime(9)

MATHEMATICA

Select[Range[1, 100, 2], And@@Not/@PrimeQ/@PrimePi/@First/@FactorInteger[#]&]

CROSSREFS

Cf. A000040, A006450, A007821, A018252, A056239, A076610, A112798, A302242, A320533, A320628, A320630, A320631, A320633.

Sequence in context: A092409 A124095 A109369 * A309649 A088982 A176406

Adjacent sequences:  A320626 A320627 A320628 * A320630 A320631 A320632

KEYWORD

nonn

AUTHOR

Gus Wiseman, Oct 18 2018

STATUS

approved

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Last modified October 16 03:15 EDT 2019. Contains 328038 sequences. (Running on oeis4.)