a(1)=1; for n>1, a(n) is the smallest positive integer for which sigma(a(n)) is a proper multiple of sigma(a(n-1)).
A237352
a(1)=1; for n>1, a(n) is the smallest positive integer for which sigma(a(n)) is a proper multiple of sigma(a(n-1)).
Terms
- a(0) =1a(1) =2a(2) =5a(3) =6a(4) =14a(5) =30a(6) =66a(7) =138a(8) =210a(9) =462a(10) =930a(11) =1974a(12) =3810a(13) =6510a(14) =14322a(15) =26670a(16) =58674a(17) =118110a(18) =245730a(19) =498666a(20) =826770a(21) =1720110a(22) =3784242a(23) =7617630a(24) =15728610a(25) =27524910a(26) =53323410a(27) =110100270a(28) =218453970a(29) =480598734
External references
- oeis: A237352