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A227432 Difference between 10^n and the first prime of gap 4 > 10^n. 3
3, 3, 9, 99, 189, 33, 453, 123, 93, 597, 69, 189, 279, 1173, 399, 1719, 2733, 2493, 87, 753, 213, 537, 249, 663, 3309, 123, 279, 597, 2253, 2853, 3237, 2403, 6747, 1257, 3069, 159, 3933, 2277, 6057, 7557, 1869, 17043, 2463, 17013, 4923, 4767, 15723, 2607, 2763 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
As N increases, the ratio sum(a(n)/n^2)/N for n = 1 to N tends to 4.
LINKS
EXAMPLE
10^1+3 = 13, 13 and 17 primes of gap 4, a(1)=3.
10^2+3 = 103, 103 and 107 primes of gap 4, a(2)=3.
PROG
(PARI) a(n) = {p = nextprime(10^n); q = nextprime(p+1); while (q-p != 4, r = nextprime(q+1); p = q; q = r); p - 10^n; } \\ Michel Marcus, Feb 24 2018
CROSSREFS
Cf. A124001.
Sequence in context: A115564 A122961 A165421 * A100731 A072004 A095271
KEYWORD
nonn
AUTHOR
Pierre CAMI, Jul 11 2013
EXTENSIONS
Missing a(246) inserted into b-file by Andrew Howroyd, Feb 24 2018
STATUS
approved

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Last modified March 2 10:43 EST 2024. Contains 370466 sequences. (Running on oeis4.)