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A244863 Semiprimes whose digit sum is a perfect square. 3
4, 9, 10, 22, 121, 169, 178, 187, 202, 259, 295, 301, 358, 394, 466, 493, 529, 538, 565, 583, 655, 718, 745, 763, 781, 799, 817, 835, 862, 871, 889, 898, 934, 943, 961, 979, 1003, 1111, 1159, 1177, 1186, 1195, 1267, 1285, 1294, 1339, 1357, 1366, 1393, 1438, 1465 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A028839.

LINKS

K. D. Bajpai, Table of n, a(n) for n = 1..10000

EXAMPLE

178 is in the sequence because 178 = 2*89 (semiprime) and 1+7+8 = 16 (square).

187 is in the sequence because 187 = 11*17 (semiprime) and 1+8+7 = 16 (square).

MAPLE

select(n -> numtheory:-bigomega(n)=2 and issqr(convert(convert(n, base, 10), `+`)),

[$1..3000]); # Robert Israel, Jul 09 2014

MATHEMATICA

Select[Range[3000], PrimeOmega[#] == 2 && IntegerQ[Sqrt[Apply [Plus, IntegerDigits[#]]]] &]

CROSSREFS

Cf. A007953, A028839, A048519.

Cf. A107288 (Primes whose digit sum is square).

Sequence in context: A177927 A062398 A030754 * A077584 A093896 A191905

Adjacent sequences:  A244860 A244861 A244862 * A244864 A244865 A244866

KEYWORD

nonn,base

AUTHOR

K. D. Bajpai, Jul 07 2014

STATUS

approved

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Last modified November 18 09:55 EST 2019. Contains 329261 sequences. (Running on oeis4.)