A244863 Semiprimes whose digit sum is a perfect square.

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

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 A332449

Adjacent sequences: A244860 A244861 A244862 * A244864 A244865 A244866

Keyword

nonn,base

Author

K. D. Bajpai, Jul 07 2014

Status

approved