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 A240895 Consider a number of k digits n = d_(k)*10^(k-1) + d_(k-1)*10^(k-2) + … + d_(2)*10 + d_(1). Sequence lists the numbers n such that sigma(n) - n = Sum_{i=1..k-1}{sigma(Sum_{j=1..i}{d_(j)*10^(j-1)})}} (see example below). 2
 11, 25, 31, 41, 61, 71, 341, 671, 2119, 10231, 39579, 52231, 60341, 402959, 1288689, 1393059, 1956759, 16752951, 108659999, 181704519, 794033191, 1062726071, 3518397571, 4062296851, 4085227151, 7015608139 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(27) > 10^10. - Giovanni Resta, Apr 16 2014 LINKS EXAMPLE If n = 52231, starting from the least significant digit, let us cut the number into the set 1, 31, 231, 2231. We have: sigma(1) = 1; sigma(31) = 32; sigma(231) = 384; sigma(2231) = 2352 and 1 + 32 + 384 + 2352 = 2769 = sigma(52231) - 52231. MAPLE with(numtheory); P:=proc(q) local a, k, n; for n from 2 to q do a:=0; k:=1; while (n mod 10^k)

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Last modified January 22 04:27 EST 2020. Contains 331133 sequences. (Running on oeis4.)