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 A196938 a(n) is the prime number that is the center element (3rd) of a 5-terms arithmetic progression prime chain. 2
 17, 29, 67, 71, 89, 97, 101, 131, 163, 167, 173, 191, 193, 197, 211, 233, 241, 257, 263, 269, 283, 307, 313, 317, 337, 347, 373, 419, 433, 443, 449, 457, 461, 463, 467, 479, 491, 503, 509, 521, 523, 547, 577, 599, 601, 607, 617, 619, 631, 641, 643, 677, 683 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The Mathematica program gives the first 53 terms. The Mathematica program is also good for finding sequences with any odd number of terms. LINKS Lei Zhou, Table of n, a(n) for n = 1..10000 EXAMPLE {5,13,,23,29} is a 5-term arithmetic progression prime chain, so a(1)=17; (for all primes smaller than 17, no such chains exist) {5,17,.41,53} is a 5-term arithmetic progression prime chain, so a(2)=29; (for all primes in between 17 and 29, no such chains exist) MATHEMATICA terms = 5; max=53; i = 1; step = (terms - 1)/2; Table[While[i++; p = Prime[i]; found = 0; j = 0; While[j++; df = 6*j; (p > (step*df)) && (found == 0), found = 1; Do[If[(! PrimeQ[p - k*df]) || (! PrimeQ[p + k*df]), found = 0], {k, 1, step}]]; found == 0]; p, {ct, 1, max}] CROSSREFS Cf. A033451. Sequence in context: A089629 A007349 A154616 * A225943 A069755 A076727 Adjacent sequences:  A196935 A196936 A196937 * A196939 A196940 A196941 KEYWORD nonn,easy AUTHOR Lei Zhou, Oct 07 2011 STATUS approved

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Last modified October 20 22:36 EDT 2019. Contains 328291 sequences. (Running on oeis4.)