A071923 - OEIS

A071923

a(n) is the prime p such that pi(n^2, (n+1)^2+1) = pi((n+1)^2, p) where pi(s,t) = pi(t) - pi(s) is the number of primes between s and t.

7, 13, 19, 37, 41, 67, 73, 101, 107, 149, 163, 193, 227, 239, 281, 337, 353, 397, 433, 479, 523, 577, 607, 677, 733, 769, 829, 907, 953, 1013, 1091, 1151, 1229, 1289, 1373, 1439, 1489, 1601, 1667, 1777, 1867, 1907, 2027, 2099, 2237, 2281, 2389, 2543, 2591

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..49.

EXAMPLE

a(1)=7 because pi(1,4)=2 and pi(4,7)=2.

PROG

(PARI) pi(m, n)=local(i, pic); pic=0; forprime (i=m, n, pic++); pic;

for (x=1, 500, xc=0; px=pi(x^2, (x+1)^2); forprime (y=(x+1)^2, 100000, xc++; if (xc==px, print1(y, ", "); break)))

CROSSREFS

Sequence in context: A208720 A208776 A108295 * A344045 A048646 A152087

Adjacent sequences: A071920 A071921 A071922 * A071924 A071925 A071926

KEYWORD

nonn

AUTHOR

Jon Perry, Jun 14 2002

EXTENSIONS

Title clarified and offset corrected by Sean A. Irvine, Aug 21 2024

STATUS

approved