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Search: id:A103801
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| 4, 6, 10, 14, 22, 26, 34, 38, 62, 78, 106, 138, 142, 162, 190, 194, 230, 258, 274, 278, 302, 402, 430, 458, 494, 498, 534, 550, 618, 670, 674, 690, 694, 742, 770, 814, 822, 902, 934, 1014, 1030, 1038, 1062, 1090, 1102, 1106, 1142, 1146, 1182, 1222, 1234
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OFFSET
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1,1
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EXAMPLE
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A019565(4)=5, 3 and 7 are both primes, so a(1)=4;
A019565(6)=15, 13 and 17 are both primes, so a(2)=6;
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MATHEMATICA
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A019565 = Function[tn, k1 = tn; o = 1; tt = 1; While[k1 > 0, k2 = Mod[k1, 2]; If[k2 == 1, tt = tt*Prime[o]]; k1 = (k1 - k2)/2; o = o + 1]; tt]; Do[cp1 = A019565[n] - 2; cp2 = cp1 + 4; If[PrimeQ[cp1] && PrimeQ[cp2], Print[n]], {n, 0, 20000}]
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CROSSREFS
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Cf. A019565, A103799, A103800.
Adjacent sequences: A103798 A103799 A103800 this_sequence A103802 A103803 A103804
Sequence in context: A091376 A100484 A076924 this_sequence A141247 A049632 A061227
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KEYWORD
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easy,nonn
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AUTHOR
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Lei Zhou (lzhou5(AT)emory.edu), Feb 22 2005
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