

A307629


Let decimal expansion of n be d_1 d_2 ... d_k; a(n) = Sum_{i=1..k1} Sum_{j=i+1..k} (d_i + d_j).


2



0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 2, 4, 6
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OFFSET

0,12


COMMENTS

More than the usual number of terms are shown in order to distinguish this from related sequences.
Starts to differ from A093882 at A093882(101)=22 <> a(101)=4.  R. J. Mathar, May 06 2019


LINKS

Michael De Vlieger, Table of n, a(n) for n = 0..10000


FORMULA

From Alois P. Heinz, Apr 19 2019: (Start)
a(n) = A007953(n) * (A055642(n)1).
a(n) = A110805(n)  A007953(n). (End)


EXAMPLE

For n<10 there is only one decimal digit so a(n)=0.
a(102) = 1+0 + 1+2 + 0+2 = 6.


MAPLE

a:= n> (d> (nops(d)1)*add(i, i=d))(convert(n, base, 10)):
seq(a(n), n=0..120); # Alois P. Heinz, Apr 19 2019


MATHEMATICA

Array[Total@ Flatten@ Subsets[IntegerDigits@ #, {2}] &, 103, 0] (* Michael De Vlieger, Apr 19 2019 *)


CROSSREFS

Cf. A007953, A055642, A110805, A138953.
Suggested by A307560.
Sequence in context: A117230 A093882 A138953 * A053392 A114925 A043270
Adjacent sequences: A307626 A307627 A307628 * A307630 A307631 A307632


KEYWORD

nonn,look,base


AUTHOR

N. J. A. Sloane, Apr 19 2019


STATUS

approved



