1,1

This sequence is infinite. See the comment dated Nov 19 2012 in A060355. - Franklin T. Adams-Watters, Nov 09 2013

Donovan Johnson, Table of n, a(n) for n = 1..24 (terms < 10^22)

8 and 9 are powerful and although 8 = 4*1*(1+1), 1+1 is not powerful so 8 is in this sequence.

288 and 289 are powerful but 288 = 4*8*(8+1) and both 8 and 8+1 are powerful so 288 is not in this sequence.

675 and 676 are powerful and 675 is not of the form 4m(m+1) so 675 is in this sequence.

Subsequence of A060355 and hence of A001694.

Sequence in context: A286394 A101180 A128875 * A278857 A202910 A332168

Adjacent sequences: A199798 A199799 A199800 * A199802 A199803 A199804

nonn

Charles R Greathouse IV, Nov 10 2011

approved