A239521 Prime powers (A025475) such that the distance to the nearest prime power is an oblong number (A002378).

25, 27, 2209, 3481, 3721, 6859, 6889, 18769, 22201, 22801, 157609, 1079521, 1630729, 1635841, 2621161, 2627641, 2825761, 3179089, 5257849, 5276209, 7447441, 7458361, 17032129, 17048641, 34304449, 34351321, 40436881, 40462321, 75290329, 75359761, 137288089, 137334961

Offset

1,1

Links

Table of n, a(n) for n=1..32.

Prog

(PARI) lista(nn) = {precp = 1; currp = 4; for (nextp=5, nn, if (is_A025475(nextp), if (currp - precp < nextp - currp, tt = currp - precp, tt = nextp - currp); if (!(tt % 2) && ispolygonal(tt/2, 3), print1(currp, ", ")); precp = currp; currp = nextp; ); ); } \\ Michel Marcus, Apr 11 2014

Crossrefs

Cf. A002378, A025475, A239520 - A239523.

Sequence in context: A015734 A221617 A083806 * A345509 A295748 A254226

Adjacent sequences: A239518 A239519 A239520 * A239522 A239523 A239524

Keyword

nonn

Author

Alex Ratushnyak, Mar 20 2014

Status

approved