This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A146560 #10 Jul 22 2025 06:14:56 %S A146560 21,57,65,69,77,129,177,209,221,237,309,329,365,381,417,437,497,501, %T A146560 545,597,681,689,717,785,905,965,1037,1101,1121,1257,1317,1397,1437, %U A146560 1497,1509,1541,1569,1577,1661,1757,1821,1829,1865,1929,1977,1985,2201,2369,2577,2589,2669,2705,2885,2901 %N A146560 Squarefree semiprimes n such that n+1 is squarefree and n+2 is prime. %H A146560 Harvey P. Dale, <a href="/A146560/b146560.txt">Table of n, a(n) for n = 1..1000</a> %F A146560 (A006881 INTERSECT A040976) INTERSECT A005117 %t A146560 Select[Range[3000],PrimeOmega[#]==2&&SquareFreeQ[#]&&SquareFreeQ[#+1]&&PrimeQ[#+2]&] (* _Harvey P. Dale_, Jan 20 2020 *) %Y A146560 Cf. A077064, A146319. %K A146560 easy,nonn %O A146560 1,1 %A A146560 _Giovanni Teofilatto_, Nov 01 2008 %E A146560 Definition corrected and more terms supplied by _R. J. Mathar_, Nov 02 2008