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A024620 Positions of primes among the powers of primes (A000961). 4
2, 3, 5, 6, 9, 10, 12, 13, 14, 17, 18, 20, 21, 22, 23, 25, 26, 27, 29, 30, 31, 32, 34, 35, 36, 37, 38, 39, 40, 41, 44, 46, 47, 48, 49, 50, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 70, 72, 73, 74, 75, 76, 77, 78, 80, 81, 82, 83, 84, 85, 86, 88, 89, 90, 91, 93, 94 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

A025474(a(n)) = 1. - Reinhard Zumkeller, May 01 2015

a(n) = A001222(A056604(n)) + 1. - Eric Desbiaux, Dec 02 2018

From Ridouane Oudra, Oct 18 2020: (Start)

a(n) = A027883(n) + 1;

a(n) = A025528(A000040(n)) + 1;

a(n) = A065515(A000040(n)). (End)

MATHEMATICA

a[n_] := PrimeOmega[LCM @@ Range@Prime@n] + 1; Array[a, 100] (* Amiram Eldar, Dec 02 2018 *)

PROG

(PARI) lista(nn)=vec = vector(nn, i, i); powpr = select((i->((omega(i)==1) || (i==1))), vec); for (i = 1, #powpr, if (isprime(powpr[i]), print1(i, ", ")); ); \\

(Haskell)

a024620 n = a024620_list !! (n-1)

a024620_list = filter ((== 1) . a025474) [1..]

-- Reinhard Zumkeller, May 01 2015

CROSSREFS

Complement of A024621.

Cf. A001222 (bigomega), A025474, A056604, A027883.

Cf. A025528, A065515, A000040.

Sequence in context: A189224 A018762 A059746 * A232527 A188375 A047331

Adjacent sequences:  A024617 A024618 A024619 * A024621 A024622 A024623

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified April 17 03:58 EDT 2021. Contains 343059 sequences. (Running on oeis4.)