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 A132705 #8 Mar 26 2025 20:23:57 %S A132705 2,3,4,5,16,7,20,9,64,25,28,13,80,15,36,35,256,19,100,21,112,45,52,25, %T A132705 320,49,60,125,144,31,140,33,128,65,76,63,400,49,84,75,448,43,180,45, %U A132705 208,175,100,49,1280,81,196,95,240,55,500,91,576,105,124,60 %N A132705 For an integer n with prime factorization (p_1)*(p_2)*(p_3)* ... *(p_k), a(n) = (p_1+2)*(p_2+2)*(p_3+2)* ... *(p_k+2). %C A132705 a(0)=2 and a(1)=3 by convention. For an integer n with prime factorization prime(i_1)*prime(i_2)*prime(i_3)* ... *prime(i_k), a(n) = A052147(i_1)*A052147(i_2)*A052147(i_3)* ... *A052147(i_k). This sequence is to p+2 as A064478 is to p+1 for primes p. %C A132705 If a(1) were 1 rather than 3, the sequence would be completely multiplicative with a(p) = p + 2. - _Charles R Greathouse IV_, Sep 02 2009 %o A132705 (Python) %o A132705 from math import prod %o A132705 from sympy import factorint %o A132705 def A132705(n): return prod((p+2)**e for p,e in factorint(n).items()) if n!=1 else 3 # _Chai Wah Wu_, Mar 26 2025 %Y A132705 Cf. A000040, A003958, A003959, A064476, A064479, A052147, A064478. %K A132705 easy,nonn %O A132705 0,1 %A A132705 _Jonathan Vos Post_, Nov 16 2007