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A231964
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Lesser member of untouchable twin pairs, that is, such that a(n) and a(n)+2 are untouchable (A005114).
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8
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246, 288, 290, 304, 322, 324, 406, 472, 516, 518, 624, 626, 668, 748, 766, 782, 802, 892, 894, 896, 934, 964, 1044, 1078, 1146, 1148, 1160, 1246, 1254, 1256, 1312, 1314, 1316, 1346, 1404, 1418, 1420, 1506, 1508, 1680, 1716, 1774, 1820, 1838, 1840, 1842, 1894
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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There are 2673 terms in this sequence when the 8153 terms of A005114, up to 60000, are taken into account.
Note that some numbers come up by pairs like (288,290) or (322,324), corresponding to untouchable triples. Others come up by groups of 3 like (892,894,896) or (1312,1314,1316), corresponding to untouchable quadruplets. For higher n-tuplets, see A231965.
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LINKS
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EXAMPLE
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246 and 248 are untouchable, so 246 is in this sequence.
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PROG
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(PARI) lista() = {v = readvec("untouchable.log"); for (i=1, #v, vi = v[i]; if (vecsearch(v, vi+2, ), print1(vi, ", ")); ); } \\ Michel Marcus, Nov 16 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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