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a(n) is the smallest prime p(k) such that the gaps between the primes p(k), p(k+1), p(k+2), ..., p(k+n) are 2, 4, 6, ... 2n.
5

%I #31 Nov 17 2021 13:24:45

%S 3,5,17,347,13901,128981,128981,113575727,2426256797,137168442221,

%T 4656625081181,101951758179851,484511389338941,221860944705726407

%N a(n) is the smallest prime p(k) such that the gaps between the primes p(k), p(k+1), p(k+2), ..., p(k+n) are 2, 4, 6, ... 2n.

%D Steven Kahan, 2-4-6-8...Prime Gaps That Appreciate, J. Rec. Math., Vol. 25 #1, pp. 44-46, 1993

%F a(n) = min{x : x = prime; {x + k + k^2} = primes following x for k=1, .., n}

%e Consider consecutive primes 347, 349, 353, 359, 367. The gaps are 2, 4, 6, 8, so a(4)=347.

%Y Cf. A263049.

%K nonn,more

%O 1,1

%A _Robert G. Wilson v_

%E Corrected and extended by _Jud McCranie_, Jun 24 2000

%E a(11)-a(13) from _Dmitry Petukhov_, Oct 03 2015

%E a(14) from _Dmitry Petukhov_, Jul 06 2016