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A236181 Let x(1)x(2)... x(q) denote the decimal expansion of a number n with q odd. The sequence lists the squares n such that the central digit equals the sum of the other digits. 0
121, 484, 10201, 10816, 40804, 72900, 1002001, 1008016, 3059001, 4008004, 100020001, 100080016, 151290000, 210250000, 216090000, 234090000, 313290000, 400080004, 10000200001, 10000800016, 10210900401, 11003800201, 11020800400, 14101800001, 30101903001, 30310810000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The numbers that are both perfect squares and palindromes (A033934) are in the sequence.  The numbers 104^2, 1004^2, 10004^2,... are in the sequence.

LINKS

Table of n, a(n) for n=1..26.

EXAMPLE

10201 = 101^2 is in the sequence because the central digit 2 equals the sum of the other digits 1+0+0+1.

MAPLE

with(numtheory):for n from 2 to 6 do:m:=2*n-2:m1:=floor(sqrt(10^m)):m2:=floor(sqrt(10^(m+1)-1)):for k1 from m1 to m2 do:k:=k1^2:x:=convert(k, base, 10):n1:=nops(x):s:=sum('x[j]', 'j'=1..n1):s1:=s-x[n]:if x[n]=s1 then printf(`%d, `, k):else fi:od:od:

CROSSREFS

Cf. A000290, A033934.

Sequence in context: A062555 A017390 A110722 * A077432 A017654 A183448

Adjacent sequences:  A236178 A236179 A236180 * A236182 A236183 A236184

KEYWORD

nonn,base

AUTHOR

Michel Lagneau, Jan 19 2014

STATUS

approved

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Last modified September 27 21:12 EDT 2021. Contains 347698 sequences. (Running on oeis4.)