A113856 - OEIS

%I #9 Jan 12 2022 18:59:09

%S 833,7425,17325,329175,7194825,7759125,275380875,2256271875,

%T 28879228125,152156958525,22342629684375,2588036347771875,

%U 17452999438621621875,499296818283476338125,894477156692665528125

%N Numbers k such that k = (2*d_1 + 1)*(2*d_2 + 1)*...*(2*d_m + 1) where d_1 d_2 ... d_m is the decimal expansion of k.

%e 833 = (2*8 + 1) * (2*3 + 1) * (2*3 + 1) = 17*7*7.

%t Select[Range[776*10^4],Times@@(2#+1&/@IntegerDigits[#])==#&] (* The program generates the first 6 terms of the sequence. To generate more, increase the Range constant but the program may take a long time to run. *) (* _Harvey P. Dale_, Jan 12 2022 *)

%K base,nonn,more

%O 1,1

%A _Giovanni Resta_, Jan 25 2006