login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A301925 a(n) is the smallest prime p such that the gap between p and the next prime is 4*n. 0
7, 89, 199, 1831, 887, 1669, 2971, 5591, 9551, 19333, 15683, 28229, 19609, 82073, 43331, 89689, 134513, 31397, 212701, 542603, 461717, 544279, 927869, 360653, 396733, 1388483, 2238823, 370261, 5845193, 1895359, 6752623, 3851459, 1357201, 6371401, 7621259, 11981443, 2010733, 8421251 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
It is a plausible conjecture that a(n) always exists. - N. J. A. Sloane, Jul 21 2018
LINKS
EXAMPLE
a(1) = A058620(1) = 7;
a(2) = 89 because (97 - 89)/4 = 8/4 = 2, a prime; etc.
MATHEMATICA
t[_] := 0; p = 3; q = 5; While[p < 10000000, d = (q - p)/2; If[ t[d] == 0, t[d] = p]; p = q; q = NextPrime@ q]; t@# & /@ (2 Range@ 30)
PROG
(PARI) a(n) = {my(p = 2); forprime(q=3, , my(d = q-p); if (d/(2*n)==2, return (p)); p = q; ); } \\ Michel Marcus, Jun 22 2018; corrected Jun 15 2022
CROSSREFS
Inspired by A058620. A bisection of A000230.
Sequence in context: A220357 A054678 A259360 * A036902 A142204 A071363
KEYWORD
nonn
AUTHOR
EXTENSIONS
Name corrected by Jinyuan Wang, Jun 15 2022
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 23 04:31 EST 2024. Contains 370267 sequences. (Running on oeis4.)