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A068833 Start of the first occurrence of exactly n consecutive squares with digit sum also a square. 2
16, 36, 900, 3364, 0, 123409881, 10000, 81, 2120219933855716, 91361386718598177458046950625 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..9.

EXAMPLE

a(7) = 81 as the sums of the digits of the 7 consecutive squares 81, 100, 121, 144, 169, 196, 225 are squares, but the digit sums of 64 and 256 are not.

MATHEMATICA

l[n_] := Module[{k}, For[k=0, IntegerQ[Sqrt[Plus@@IntegerDigits[(n+k)^2]]], k++, Null]; k]; Clear[a]; For[n=0, True, n+=ln+1, If[a[ln=l[n]]==-1, Null, Null, a[ln]=n; Print["a(", ln, ")=", n^2]]]

CROSSREFS

Cf. A061910, A293832.

Sequence in context: A218523 A300535 A053893 * A116190 A070587 A275186

Adjacent sequences:  A068830 A068831 A068832 * A068834 A068835 A068836

KEYWORD

hard,more,nonn,base

AUTHOR

Amarnath Murthy, Mar 09 2002

EXTENSIONS

Edited by Dean Hickerson, Oct 28 2002

a(9) from Giovanni Resta, Aug 27 2018

STATUS

approved

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Last modified December 5 06:12 EST 2021. Contains 349532 sequences. (Running on oeis4.)