A192282 Numbers n such that n and n+1 have same sum of anti-divisors.
1, 8, 17, 120, 717, 729, 957, 8097, 10785, 12057, 35817, 44817, 52863, 58677, 59757, 76759, 95397, 102957, 114117, 119337, 182157, 206097, 215997, 230037, 253977, 263877, 269277, 271797, 295377, 321417, 402657, 435477, 483117, 485637, 510837, 586797, 589317
Offset: 1
Keywords
Examples
Anti-divisors of 717 are 2, 5, 6, 7, 35, 41, 205, 287, 478 and their sum is 1066. Anti-divisors of 718 are 3, 4, 5, 7, 35, 41, 205, 287, 479 and their sum is 1066.
Links
- Donovan Johnson, Table of n, a(n) for n = 1..1000
Programs
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Maple
with(numtheory); P:=proc(n) local a,b,i,k; b:=2; for i from 4 to n do a:=0; for k from 2 to i-1 do if abs((i mod k)- k/2) < 1 then a:=a+k; fi; od; if a=b then print(i-1); fi; b:=a; od; end: P(200000);
Extensions
Initial term a(1)=1 inserted, a(2)=9 through a(20)=119337 verified, and a(21)-a(28) added by John W. Layman, Aug 04 2011
Comments