A117993 Heptagonal numbers with only odd digits.

1, 7, 55, 1177, 3553, 9517, 11799, 13579, 17935, 31753, 71995, 93799, 97713, 117397, 135373, 371911, 377719, 599515, 733597, 777573, 1131313, 1331155, 1371591, 1555119, 3391315, 3731377, 3979717, 5131573, 7137715, 7333353, 9193933, 13755771, 13979515

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..382 (* All terms up to the 1 millionth heptagonal number. *)

Mathematica

Select[Table[n (5n-3)/2, {n, 4000}], AllTrue[IntegerDigits[#], OddQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Feb 28 2015 *)
Select[PolygonalNumber[7, Range[2500]], AllTrue[IntegerDigits[#], OddQ]&] (* Harvey P. Dale, Dec 19 2025 *)

Crossrefs

Cf. A000566, A117994.

Sequence in context: A227544 A094656 A239156 * A055056 A305282 A197228

Adjacent sequences: A117990 A117991 A117992 * A117994 A117995 A117996

Keyword

base,nonn

Author

Luc Stevens (lms022(AT)yahoo.com), May 03 2006

Extensions

Corrected by Harvey P. Dale, Feb 28 2015

Status

approved