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A308495 a(n) is the position of the first occurrence of prime(n) in A027748. 2
2, 3, 5, 8, 13, 16, 22, 25, 32, 41, 45, 55, 62, 66, 73, 83, 94, 98, 109, 117, 120, 132, 138, 150, 166, 173, 177, 185, 188, 196, 224, 231, 243, 247, 267, 271, 284, 295, 303, 315, 327, 331, 353, 356, 364, 368, 394, 419, 426, 430, 439, 452, 456, 475, 487, 500 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..10000

FORMULA

A027748(a(n)) = A000040(n).

a(n) = 1 + A013939(A000040(n)). - Charlie Neder, Jun 04 2019

a(n) = A082186(A000040(n)). - Alois P. Heinz, Jun 06 2019

EXAMPLE

For n = 5: a(5) = 13, A027748(13) = A000040(5) = 11.

MAPLE

b:= proc(n) option remember; `if`(n=1, 1,

      b(n-1) +nops(ifactors(n)[2]))

    end:

a:= n-> b(ithprime(n)):

seq(a(n), n=1..60);  # Alois P. Heinz, Jun 06 2019

MATHEMATICA

b[n_] := b[n] = If[n == 1, 1, b[n-1] + PrimeNu[n]];

a[n_] := b[Prime[n]];

Array[a, 60] (* Jean-Fran├žois Alcover, Nov 27 2020, after Alois P. Heinz *)

PROG

(Haskell)

-- expected to be part of A027748

a027748_list = concat (map a027748_row [1..])

minIdx [] _ = []

minIdx _ [] = []

minIdx (a:as) (b:bs)

    | a == b = 1 : (map succ (minIdx as bs))

    | otherwise = map succ (minIdx as (b:bs))

a308495_list = minIdx a027748_list a000040_list

a308495 n = a308495_list !! (n-1)

(PARI) a(n) = 1 + sum(k=1, prime(n), omega(k)); \\ Michel Marcus, Jun 05 2019

CROSSREFS

Cf. A000040, A001221, A013939, A027748, A082186.

Sequence in context: A076591 A078695 A121367 * A221672 A241551 A070217

Adjacent sequences:  A308492 A308493 A308494 * A308496 A308497 A308498

KEYWORD

nonn

AUTHOR

Peter Dolland, Jun 01 2019

STATUS

approved

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Last modified June 15 04:47 EDT 2021. Contains 345043 sequences. (Running on oeis4.)