A256477 Numbers n for which the number of primes in the range [prime(n)*prime(n+1), prime(n+1)^2] is less than or equal to the number of primes in the range [prime(n)^2, prime(n)*prime(n+1)].

1, 10, 13, 14, 17, 20, 25, 26, 38, 39, 41, 42, 43, 44, 45, 48, 49, 50, 55, 58, 59, 61, 63, 65, 69, 73, 74, 77, 81, 86, 88, 90, 92, 96, 98, 101, 103, 106, 107, 108, 109, 110, 116, 117, 120, 121, 122, 124, 125, 128, 141, 142, 143, 145, 146, 148, 149, 151, 152, 155, 158, 159, 166, 169

Offset

1,2

Comments

Positions where A256470 is zero or negative.

Links

Antti Karttunen, Table of n, a(n) for n = 1..3128

Mathematica

Select[Range@ 170, Count[Range[Prime[#] Prime[# + 1], Prime[# + 1]^2], _?PrimeQ] <= Count[Range[Prime[#]^2, Prime[#] Prime[# + 1]], _?PrimeQ] &] (* Michael De Vlieger, Mar 30 2015 *)

Prog

(Scheme, with Antti Karttunen's IntSeq-library)
(define A256477 (MATCHING-POS 1 1 (lambda (n) (>= 0 (A256470 n)))))

Crossrefs

Complement: A256476.

Union of A256471 and A256475.

Cf. A256470.

Sequence in context: A087140 A226778 A061837 * A247464 A219110 A377911

Adjacent sequences: A256474 A256475 A256476 * A256478 A256479 A256480

Keyword

nonn

Author

Antti Karttunen, Mar 30 2015

Status

approved