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 A237189 Numbers k such that k+1, 2k+1, 3k+1, 4k+1 are all prime. 4
 330, 1530, 3060, 4260, 4950, 6840, 10830, 15390, 18120, 23010, 25410, 26040, 31770, 33300, 40110, 41490, 45060, 49830, 53880, 59340, 65850, 70140, 73770, 78540, 88740, 95460, 96930, 109470, 111720, 112620, 117720, 131310, 133200, 134730, 135300, 150150, 165900 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A subsequence of A064238. All terms are divisible by 30, and b(n)=a(n)/30 begins: 11, 51, 102, 142, 165, 228, 361, 513, 604, 767, 847, 868, 1059, 1110, 1337, 1383, 1502, 1661, 1796, 1978, 2195, ... LINKS Jon E. Schoenfield, Table of n, a(n) for n = 1..10000 (first 1000 terms from Giovanni Resta) FORMULA a(n) = 2*(A105653(n) + 1) = 2*A124409(n). - Hugo Pfoertner, May 03 2021 PROG (Python) import sympy from sympy import isprime for n in range(0, 100000, 2): if isprime(n+1) and isprime(2*n+1) and isprime(3*n+1) and isprime(4*n+1): print(str(n), end=', ') CROSSREFS Cf. A088250, A064238, A105653, A124409. Sequence in context: A300009 A244264 A117345 * A064262 A126997 A205993 Adjacent sequences: A237186 A237187 A237188 * A237190 A237191 A237192 KEYWORD nonn AUTHOR Alex Ratushnyak, Feb 04 2014 STATUS approved

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Last modified December 8 04:55 EST 2023. Contains 367662 sequences. (Running on oeis4.)