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 A371656 #10 Apr 02 2024 08:54:23 %S A371656 5,8,9,10,12,15,21,23,24,36,37,38,39,45,53,58,60,67,68,69,81,84,86,89, %T A371656 93,99,100,102,105,110,111,112,113,117,120,121,129,131,134,138,143, %U A371656 144,154,157,165,172,173,178,184,185,188,195,203,204,207,211,215,216,217,219,225,230,231,240,244 %N A371656 Numbers k such that k - 2 and k + 2 have the same number of prime factors, counted with multiplicity. %C A371656 Numbers k such that A001222(k - 2) = A001222(k + 2). %H A371656 Robert Israel, <a href="/A371656/b371656.txt">Table of n, a(n) for n = 1..10000</a> %e A371656 a(4) = 10 is a term because 10 - 2 = 8 = 2^3 and 10 + 2 = 12 = 2^2 * 3 are both products of 3 primes, counted with multiplicity. %p A371656 M:= map(numtheory:-bigomega, [$1..10^3]): %p A371656 select(k -> M[k-2] = M[k+2], [$3 .. 10^3 - 2]); %t A371656 Select[Range[3,245],PrimeOmega[#-2]==PrimeOmega[#+2]&] (* _Stefano Spezia_, Apr 01 2024 *) %Y A371656 Cf. A001222. Contains A371622. %K A371656 nonn %O A371656 1,1 %A A371656 _Robert Israel_, Apr 01 2024 %E A371656 Suggested by _Joerg Arndt_