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 A175807 A007318-perfect numbers. 6
 2, 3, 4, 5, 12, 22, 26, 154 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS See definition in comment to A175522. The definition is applied to the flattened view of the binomial coefficients with a single index, without regard to fact that A007318 is a triangle. No more terms up to 10^6. - Michel Marcus, Feb 07 2016 LINKS EXAMPLE Since A007318(1)+ A007318(2)+ A007318(3)+ A007318(4)+ A007318(6)=6= A007318(12), then 12 is in the sequence. MAPLE A007318 := proc(n) option remember; local t, r; t := 0 ; for r from 0 do if t+r+1 > n then return binomial(r, n-t) ; end if; t := t+r+1 ; end do: end proc: isA175807 := proc(n) m := 0 ; for d in numtheory[divisors](n) minus {n} do m := m+A007318(d) ; end do; m = A007318(n) ; end proc: for n from 1 do if isA175807(n) then printf("%d, \n", n); end if; end do: # R. J. Mathar, Dec 05 2010 PROG (PARI) b(n) = {my(m = 1); while (m*(m+1)/2 < n, m++); if (! ispolygonal(n, 3), m--); binomial(m, n - m*(m+1)/2); } isok(n) = sumdiv(n, d, (d

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Last modified July 29 22:26 EDT 2021. Contains 346346 sequences. (Running on oeis4.)