A270895 Sierpiński numbers that are squares.

18213931681, 5044241991721, 6093734165401, 6278567569849, 17919144076201, 52536446729209, 56470430531761, 72659547739249, 107737943736721, 123343213788001, 136925780937841, 170306127919321, 211292941174561, 296693149397089, 321058916825689

Offset: 1

Author

Arkadiusz Wesolowski, Mar 25 2016

Keywords

• nonn
• hard

Comments

This sequence contains infinitely many numbers that end in 5. See also A233469.

Links

• Wikipedia, Sierpinski number

Crossrefs

Cf. A076336, A233469, A270896.

Formula

A000290 INTERSECT A076336.

a(n) = A270896(n)^2.