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A260702 Numbers n such that 3*n and n^2 have the same digit sum. 1
0, 3, 6, 9, 12, 15, 18, 21, 30, 33, 39, 45, 48, 51, 60, 66, 90, 96, 99, 102, 105, 111, 120, 123, 129, 132, 150, 153, 156, 159, 162, 165, 180, 189, 195, 198, 201, 210, 225, 231, 246, 252, 255, 261, 285, 300, 330, 333, 348, 351, 390, 399, 429, 450, 453, 459, 462 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

All terms are multiple of 3.

LINKS

Table of n, a(n) for n=1..57.

FORMULA

A007953(A008585(a(n))) = A007953(A000290(a(n))).

EXAMPLE

159 is in the sequence because 159^2 = 25281 and 3*159 = 477 have the same digit sum: 18.

MATHEMATICA

Select[Range[0, 500], Total[IntegerDigits[3 #]] == Total[IntegerDigits[#^2]] &]

PROG

(MAGMA) [n: n in [0..500] | &+Intseq(3*n) eq &+Intseq(n^2)];

(PARI) isok(n) = sumdigits(3*n) == sumdigits(n^2); \\ Michel Marcus, Nov 17 2015

(Sage) [n for n in (0..500) if sum((3*n).digits())==sum((n^2).digits())] # Bruno Berselli, Nov 17 2015

CROSSREFS

Cf. A000290, A007953, A008585, A049343, A058369.

Sequence in context: A329844 A127451 A022844 * A262712 A195934 A195933

Adjacent sequences:  A260699 A260700 A260701 * A260703 A260704 A260705

KEYWORD

nonn,base,easy

AUTHOR

Vincenzo Librandi, Nov 17 2015

STATUS

approved

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Last modified January 21 16:22 EST 2020. Contains 331114 sequences. (Running on oeis4.)