A073123 - OEIS

A073123

a(n) is the largest number such that pi(a(n)) = prime(n).

4, 6, 12, 18, 36, 42, 60, 70, 88, 112, 130, 162, 180, 192, 222, 250, 280, 292, 336, 358, 372, 408, 432, 462, 520, 556, 568, 592, 600, 618, 718, 742, 786, 808, 862, 880, 928, 970, 996, 1032, 1068, 1090, 1162, 1180, 1212, 1222, 1300, 1422, 1438, 1450, 1480

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OFFSET

1,1

COMMENTS

Primes with prime subscripts correspond to least numbers m, such that pi(m) = prime(n).

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = Max{x: A000720(x)=A000040(n)}.

a(n) = A000040(A000040(n)+1) - 1.

EXAMPLE

n=25: prime(25)=97; for 12 terms X = {509, 510, 511, 512, 513, 514, 515, 516, 517, 518, 519, 520}, pi(X)=97. Largest is a(25)=520, smallest is A006450(25), number of terms = A073124(25).

MAPLE

seq(ithprime(ithprime(n)+1)-1, n=1..100); # Robert Israel, May 14 2018

CROSSREFS

Cf. A000720, A000040, A006450, A073124.

Equals A072677(n) - 1.

Sequence in context: A258838 A377067 A034425 * A079865 A059961 A027856

Adjacent sequences: A073120 A073121 A073122 * A073124 A073125 A073126

KEYWORD

nonn

AUTHOR

Labos Elemer, Jul 16 2002

EXTENSIONS

Edited by Robert Israel, May 14 2018

STATUS

approved