A127390 -id:A127390 - cp's OEIS frontend

A140645 Digit sums of highly composite numbers.

1, 2, 4, 6, 3, 6, 9, 12, 6, 3, 9, 6, 9, 9, 12, 9, 15, 9, 9, 18, 9, 9, 9, 9, 18, 18, 9, 18, 18, 18, 18, 18, 18, 18, 36, 18, 27, 18, 18, 18, 18

Offset: 1

Parthasarathy Nambi, Jul 08 2008

Except for the first three terms, all others are multiples of 3.

			2162160 is a highly composite number whose digit sum is 18.

Amiram Eldar, Table of n, a(n) for n = 1..10000
Achim Flammenkamp, Table of 1200 Highly Composite Numbers.
Graeme McRae, Highly Composite Numbers.

Cf. A002182, A002183, A007953, A117825, A127390.

HCN=NestList[Function[last,Module[{d = DivisorSigma[0, last]},NestWhile[# + 1 &, last, DivisorSigma[0, #] <= d &]]], 1,40]; DigitSum/@HCN (* James C. McMahon, Jul 12 2025 *)

a(n) = A007953(A002182(n)). - Amiram Eldar, Nov 13 2019

A116964 Sum of all n-digit Lucas numbers.

Original entry on oeis.org

17, 181, 2008, 22269, 143285, 1692737, 18772741, 208192888, 2308894509, 14856075365, 175506357617, 1946395332181, 21585855011608, 138889450176440, 1640808956134074, 18196850168753057, 201806160812417701, 2238064619105347768, 14400335971854080600, 170122354174067662074

Offset: 1

Parthasarathy Nambi, May 27 2007

			The sum of all 1-digit Lucas numbers is 17, so a(1) = 17.
The sum of all 2-digit Lucas numbers is 181, so a(2) = 181.

Cf. A000032, A127390, A128823.

Total/@Table[Select[Table[LucasL[n],{n,0,95}], IntegerLength[#]==i&], {i,20}]  (* Harvey P. Dale, Mar 31 2011 *)
nn = 20; t = Table[0, {nn}]; k = 0; While[luc = LucasL[k]; d = IntegerLength[luc]; d <= nn, t[[d]] = t[[d]] + luc; k++]; t (* T. D. Noe, Mar 31 2011 *)

More terms from Harvey P. Dale, Mar 31 2011

cp's OEIS Frontend

A140645 Digit sums of highly composite numbers.

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