A240929 Number of 10-digit positive integers in base n where the sum of the first k digits equals the sum of the last k digits.

126, 6046, 88428, 694360, 3705741, 15192604, 51418473, 150420187, 392406145, 933294637, 2056947827, 4253047045, 8329101326, 15566783605, 27934647638, 48371293570, 81155221112, 132379936520, 210555362990, 327359243694, 498565022483, 745175639274, 1094795785319

Offset

2,1

Comments

These integers are sometimes called balanced numbers.

References

Cambridge Colleges Sixth Term Examination Papers (STEP) 2007, Paper I, Section A (Pure Mathematics), Nr. 1.

Links

Table of n, a(n) for n=2..24.

Formula

a(n) = n*(n-1)*(156190*n^7+15619*n^6+45019*n^5+14149*n^4+18139*n^3+9760*n^2+6660*n+5040)/362880

Crossrefs

Cf. A016061, A197083, A240927, A240928.

Sequence in context: A140902 A270512 A037963 * A285172 A208618 A352334

Adjacent sequences: A240926 A240927 A240928 * A240930 A240931 A240932

Keyword

nonn,base

Author

Martin Renner, Aug 03 2014

Status

approved