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 A380644 #6 Jan 29 2025 07:53:46 %S A380644 26,41,47,56,61,68,71,74,86,89,96,101,107,110,116,128,131,140,146,151, %T A380644 152,155,159,161,166,173,176,182,185,191,194,201,206,208,209,215,221, %U A380644 224,236,239,242,250,251,257,261,263,266,271,272,278,281,290,293,296,299 %N A380644 Numbers that can be expressed as 4*j*k+j+k, j,k >= 1, as well as 4*j*k-j-k, j,k >= 2. %e A380644 a(1) = 26, because 26 = 4*1*5 + 1 + 5 = 4*2*4 - 2 - 4. %e A380644 a(2) = 41: 41 = 4*1*8 + 1 + 8 = 4*3*4 - 3 - 4. %Y A380644 Cf. A054520, A124934, A125217, A125218, A380140, A380509, A380572. %K A380644 nonn %O A380644 1,1 %A A380644 _Hugo Pfoertner_, Jan 29 2025