A085774 (n / sum of digits of n) and (n+1 / sum of digits of n+1) are both semiprime.

80, 440, 735, 1014, 1160, 1274, 1547, 2023, 2820, 4806, 5490, 5565, 5875, 6137, 7215, 7748, 10309, 10520, 12104, 12255, 12256, 12257, 12614, 13112, 13481, 14120, 14415, 14705, 14927, 15317, 16434, 17118, 20174, 20175, 20538, 20604, 20804, 21307

Offset

0,1

Comments

Note the quadruple: 12255,12256,12257,12258 and the triple: 20174,20175,20176. Conjecture: sequence is infinite.

Links

Table of n, a(n) for n=0..37.

Mathematica

SequencePosition[Table[PrimeOmega[n/Total[IntegerDigits[n]]], {n, 22000}], {2, 2}][[;; , 1]] (* Harvey P. Dale, Mar 18 2023 *)

Crossrefs

Sequence in context: A273292 A234333 A234326 * A233353 A233354 A200432

Adjacent sequences: A085771 A085772 A085773 * A085775 A085776 A085777

Keyword

base,nonn

Author

Jason Earls, Jul 23 2003

Status

approved