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 A371806 Exponents k > 0 of powers of 2 such that the decimal expansion of 2^k contains more than one nonoverlapping 666 substring. 3
 220, 222, 529, 624, 648, 702, 714, 844, 846, 850, 859, 924, 925, 929, 931, 979, 981, 983, 1062, 1088, 1133, 1135, 1219, 1230, 1241, 1259, 1310, 1343, 1349, 1384, 1394, 1467, 1472, 1495, 1503, 1524, 1550, 1589, 1627, 1631, 1642, 1652, 1656, 1663, 1679, 1744, 1751 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A positive power of 2 containing 666 in its decimal expansion is called an apocalyptic number. See A371808 for a variant where overlapping substrings are counted as distinct. LINKS Paolo Xausa, Table of n, a(n) for n = 1..10000 Brady Haran and Tony Padilla, Apocalyptic Numbers, YouTube Numberphile video, 2024. Eric Weisstein's World of Mathematics, Apocalyptic Number. EXAMPLE 220 is a term because 2^220 contains more than one nonoverlapping 666 substring in its decimal expansion: 2^220 = 168499(666)66969149871(666)88442938726917102321526408785780068975640576. MATHEMATICA Select[Range[2000], StringCount[IntegerString[2^#], "666"] > 1 &] PROG (Python) def ok(n): return str(1< 1 print([k for k in range(2000) if ok(k)]) # Michael S. Branicky, Apr 07 2024 CROSSREFS Subsequence of A007356 and of A371808. Cf. A371807. Sequence in context: A157673 A064477 A371808 * A217160 A203777 A274116 Adjacent sequences: A371803 A371804 A371805 * A371807 A371808 A371809 KEYWORD nonn,easy,base AUTHOR Paolo Xausa, Apr 06 2024 STATUS approved

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Last modified September 19 12:50 EDT 2024. Contains 376012 sequences. (Running on oeis4.)