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A074985
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Squares of semiprimes A001358, composite numbers divisible by exactly 2 primes (counted with multiplicity).
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7
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16, 36, 81, 100, 196, 225, 441, 484, 625, 676, 1089, 1156, 1225, 1444, 1521, 2116, 2401, 2601, 3025, 3249, 3364, 3844, 4225, 4761, 5476, 5929, 6724, 7225, 7396, 7569, 8281, 8649, 8836, 9025, 11236, 12321, 13225, 13924, 14161, 14641, 14884, 15129
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| 4 is divisible by 2 (twice) and 4*4=16, 6 is divisible by exactly 2 and 6 and 6*6=36...
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MAPLE
| readlib(issqr): ts_kv_sp := proc(n); if (numtheory[bigomega](n)=4 and issqr(n)='true') then RETURN(n); fi; end: seq(ts_kv_sp(i), i=1..50000);
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MATHEMATICA
| Select[Range[200], PrimeOmega[#]==2&]^2 (* From Harvey P. Dale, Oct 03 2011 *)
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CROSSREFS
| Cf. A001358.
Sequence in context: A125240 A050775 A022040 * A069262 A076956 A075369
Adjacent sequences: A074982 A074983 A074984 * A074986 A074987 A074988
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KEYWORD
| base,easy,nonn
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AUTHOR
| Jani Melik (jani_melik(AT)hotmail.com), Oct 07 2002
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