A371925 Numbers that are the sum of the final digits of the squarefree divisors of some positive integer.
1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 36, 38, 40, 42, 44, 46, 48, 52, 56, 58, 60, 62, 64, 68, 72, 76, 80, 84, 88, 92, 96, 104, 108, 112, 116, 120, 124, 128, 132, 136, 144, 152, 156, 160, 164, 168, 176, 184, 188, 192, 208, 212, 216, 224, 232, 236, 240, 244, 248, 256
Offset: 1
Examples
a(10) = 16 is a term because 16 = A367503(39): the squarefree divisors of 39 are 1, 3, 13 and 39, and 1 + 3 + 3 + 9 = 16.
Links
- Robert Israel, Table of n, a(n) for n = 1..1000
Crossrefs
Cf. A367503.
Programs
-
Maple
N:= 300: # for terms <= N g:= proc(pat) local i; add(pat[i]*i,i=1..9) end proc: pats:= {[1,0,0,0,0,0,0,0,0], [1,1,0,0,0,0,0,0,0],[1,0,0,0,1,0,0,0,0],[1,1,0,0,1,0,0,0,0]}: do newpats:= select(p -> g(p)<=N, map(pat -> 2*pat, pats)) minus pats; if newpats = {} then break fi; pats:= pats union newpats od: do newpats:= select(p -> g(p) <=N, map(pat -> pat + [pat[7],pat[4],pat[1],pat[8],pat[5],pat[2],pat[9],pat[6],pat[3]], pats)) minus pats; if newpats = {} then break fi; pats:= pats union newpats od: do newpats:= select(p -> g(p)<=N, map(pat -> pat + [pat[3],pat[6],pat[9],pat[2],pat[5],pat[8],pat[1],pat[4],pat[7]], pats)) minus pats; if newpats = {} then break fi; pats:= pats union newpats od: do newpats:= select(p -> g(p)<=N, map(pat -> pat + [pat[9],pat[8],pat[7],pat[6],pat[5],pat[4],pat[3],pat[2],pat[1]], pats)) minus pats; if newpats = {} then break fi; pats:= pats union newpats od: sort(convert(map(g,pats),list));
Comments