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 A301339 a(n) is the ending digit of a prime number occurring most up to the n-th prime. If a tie exists, then the digits are concatenated in ascending order. 0
 2, 23, 235, 2357, 12357, 3, 37, 37, 3, 3, 3, 37, 137, 3, 37, 3, 3, 3, 37, 137, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 37, 37, 37, 37, 7, 37, 7, 37, 37, 37, 37, 3, 37, 37, 37, 3, 37, 37, 3, 3, 3, 3, 37, 3, 3, 3, 37, 137, 3, 3, 3, 3, 3, 3, 3, 37, 7, 7, 37, 37, 7 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS 1 occurs first at a(2766290)       2 occurs first at a(1)       3 occurs first at a(6)       7 occurs first at a(37)       9 occurs first at a(7153)      13 occurs first at a(45532)      17 occurs first at a(12655)      23 occurs first at a(2)      37 occurs first at a(7)      39 occurs first at a(429687)      79 occurs first at a(7042)     137 occurs first at a(13)     235 occurs first at a(3)     379 occurs first at a(93562)    2357 occurs first at a(4)   12357 occurs first at a(5) LINKS Caldwell and Honaker, Prime Curios!: 137 EXAMPLE a(13)=137 because primes that end with digits 1, 3, and 7 occur most frequently (exactly three times each) up to the 13th prime. MATHEMATICA With[{s = Array[Mod[Prime@ #, 10] &, 73]}, Array[FromDigits@ Last[SplitBy[#, Last]][[All, 1]] &@ SortBy[Tally@ Take[s, #], Last] &, Length@ s]] (* Michael De Vlieger, Apr 21 2018 *) PROG (PARI) lista(nn) = {my(p=1, v = vector(9)); for (n=1, nn, p = nextprime(p+1); d = p % 10; v[d] ++; vmax = vecmax(v); s = ""; for (i=1, #v, if (v[i] == vmax, s = concat(s, i)); ); print1(eval(s), ", "); ); } \\ Michel Marcus, Apr 11 2018 CROSSREFS Cf. A000040. Sequence in context: A262571 A283560 A159902 * A294268 A118385 A098739 Adjacent sequences:  A301336 A301337 A301338 * A301340 A301341 A301342 KEYWORD nonn,base AUTHOR G. L. Honaker, Jr., Mar 27 2018 EXTENSIONS a(14)-a(73) by Chuck Gaydos STATUS approved

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Last modified October 13 18:14 EDT 2019. Contains 327981 sequences. (Running on oeis4.)