1,1

S. Das Dividing by Dropping Digits

a(n)=sum_(r=1, 10^n - 1) tau(r)=A006218(A002283(n)).

We have the following a(1)=23 two-digit numbers not ending in zero: 11, 12, 13, 14, 15, 16, 17, 18, 19, 22, 24, 26, 28, 33, 36, 39, 44, 48, 55, 66, 77, 88, 99 which are divisible by their tenth digit.

k = s = 0; Do[ While[ k < 10^n - 1, k++; s = s + DivisorSigma[ 0, k ]]; Print[s], {n, 9}] (from Robert G. Wilson v Jun 05 2004)

Cf. A057494.

Sequence in context: A053067 A036906 A134733 this_sequence A015678 A014905 A133283

Adjacent sequences: A095253 A095254 A095255 this_sequence A095257 A095258 A095259

more,base,nonn

Lekraj Beedassy (blekraj(AT)yahoo.com), Jul 02 2004

a(5)-a(9) from Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 05 2004