Numbers k such that gcd(sigma(k), sigma(k+1)) > k.

Terms

a(0) =5a(1) =12a(2) =14a(3) =70a(4) =88a(5) =125a(6) =180a(7) =204a(8) =206a(9) =220a(10) =957a(11) =1253a(12) =1334a(13) =1364a(14) =1634a(15) =1673a(16) =1750a(17) =1888a(18) =1919a(19) =2685a(20) =2759a(21) =2958a(22) =2974a(23) =3127a(24) =4364a(25) =5191a(26) =7615a(27) =8142a(28) =8632a(29) =9114