A117799 Icosagonal numbers for which the sum of the digits is also an icosagonal number.

0, 1, 7337, 12692, 19505, 37505, 61337, 75440, 146432, 240752, 326801, 358400, 620417, 708401, 802217, 851312, 1007345, 1062272, 1176500, 1235801, 1422452, 1622225, 1835120, 1909001, 2061137, 2219105, 2300276, 2728001, 4010672, 4803401, 5043017, 5165012, 7026032, 7315220, 7462001

Offset

1,3

Links

Table of n, a(n) for n=1..35.

Example

7337 is in the sequence because (1) it is an icosagonal number and (2) the sum of the digits 7+3+3+7=20 is also an icosagonal number.

Prog

(PARI) isok(n) = ispolygonal(n, 20) && ispolygonal(sumdigits(n), 20); \\ Michel Marcus, Feb 27 2014

Crossrefs

Cf. A007953, A051872.

Sequence in context: A295004 A202167 A235883 * A295003 A097696 A202574

Adjacent sequences: A117796 A117797 A117798 * A117800 A117801 A117802

Keyword

nonn,base

Author

Luc Stevens (lms022(AT)yahoo.com), Apr 29 2006

Extensions

a(11) corrected by Georg Fischer, Mar 27 2024

Status

approved