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 A281702 #12 Apr 23 2017 23:59:41 %S A281702 1,2,6,10,14,18,30,34,38,42,46,50,58,66,78,86,90,94,98,106,118,130, %T A281702 134,150,154,170,174,186,190,198,206,214,218,226,234,254,258,266,270, %U A281702 274,286,294,310,314,318,326,338,350,354,366,370,394,398,406,410,426 %N A281702 Numbers k such that A001221(k) = A001221(A000326(k)). %C A281702 Numbers k such that the number of distinct prime divisors of k is equal to the number of distinct prime divisors of the pentagonal number k*(3*k-1)/2. %H A281702 Colin Barker, <a href="/A281702/b281702.txt">Table of n, a(n) for n = 1..1000</a> %t A281702 Select[Range[100], PrimeNu[#] == PrimeNu[#*(3*# - 1)/2] &] (* _G. C. Greubel_, Apr 23 2017 *) %o A281702 (PARI) select(k->omega(k)==omega(k*(3*k-1)/2), vector(500, k, k)) %Y A281702 Cf. A000326, A001221, A087370, A281703. %K A281702 nonn %O A281702 1,2 %A A281702 _Colin Barker_, Jan 28 2017