

A073946


Squares k such that k + pi(k) is a prime.


3



9, 36, 81, 121, 361, 625, 961, 3136, 6724, 8281, 9604, 10609, 12996, 13225, 19881, 25281, 38025, 39204, 40000, 43264, 44944, 45796, 47961, 60516, 64009, 79524, 80089, 80656, 83521, 86436, 90000, 93636, 103684, 117649, 121801, 129600
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OFFSET

1,1


LINKS

Robert Israel, Table of n, a(n) for n = 1..1000


EXAMPLE

a(1)=9, since 9 is a square, pi(9)=4 and 9+4=13 is a prime.


MAPLE

select(t > isprime(t + numtheory:pi(t)), [seq(i^2, i=1..1000)]); # Robert Israel, Mar 21 2017


MATHEMATICA

Select[Range[1000]^2, PrimeQ[# + PrimePi[#]] &] (* Indranil Ghosh, Mar 21 2017 *)


PROG

(PARI)
v=vector(1000);
for(n=1, 1000, v[n] = n^2);
for(n=1, 1000, if(isprime(v[n] + primepi(v[n])), print1(v[n], ", "))) \\ Indranil Ghosh, Mar 21 2017
(Python)
from sympy import primepi, isprime
N = [x**2 for x in xrange(1, 1001)]
print [n for n in N if isprime(n + primepi(n))] # Indranil Ghosh, Mar 21 2017


CROSSREFS

This sequence is a subsequence of sequence A077510. The corresponding sequence of primes is A113943 and the square roots of the original sequence is A113944.
Sequence in context: A068810 A077115 A297584 * A016766 A242538 A083353
Adjacent sequences: A073943 A073944 A073945 * A073947 A073948 A073949


KEYWORD

nonn


AUTHOR

David Garber, Nov 13 2002


STATUS

approved



