A239227 - OEIS

A239227

Primes p of the form 4k + 3 such that A000120(p) >= A000120(3p).

3, 7, 11, 23, 31, 43, 47, 59, 103, 107, 127, 139, 151, 179, 191, 199, 223, 227, 239, 251, 283, 311, 347, 359, 367, 379, 383, 431, 439, 443, 463, 479, 487, 491, 499, 503, 523, 571, 599, 607, 619, 631, 683, 691, 719, 727, 739, 743, 751, 811, 823, 827, 859, 863, 883, 887, 907, 911, 919

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OFFSET

1,1

LINKS

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

MAPLE

N:= 1000: # to get all entries <= 4*N+3

P:= select(isprime, [seq(4*i+3, i=0..N)]):

select(p -> convert(convert(p, base, 2), `+`)>=convert(convert(3*p, base, 2), `+`), P);

# Robert Israel, Jun 08 2014

PROG

(PARI) isok(p) = ((p%4) == 3) && (hammingweight(p) >= hammingweight(3*p)) && isprime(p); \\ Michel Marcus, Feb 13 2021