A130596 Partial sums of skinny numbers (A061909).

1, 3, 6, 16, 27, 39, 52, 72, 93, 115, 145, 176, 276, 377, 479, 582, 692, 803, 915, 1028, 1148, 1269, 1391, 1521, 1721, 1922, 2124, 2334, 2545, 2757, 2977, 3198, 3498, 3799, 4109, 4420, 5420, 6421, 7423, 8426, 9436, 10447, 11459, 12472, 13492, 14513, 15535

Offset: 1

Author

Jonathan Vos Post, Jun 17 2007

Keywords

• base
• easy
• nonn

Comments

The skinny partial sums of skinny numbers begin: a(1) = 1, a(2) = 3. The primes in the sequence begin: a(2) = 3, a(15) = 479, a(15) = 1721, a(38) = 6421, a(52) = 20899. The perfect powers in the sequence begin a(4) = 16 = 2^4, a(5) = 27 = 3^3, a(24) = 1521 = 39^2.

Examples

			a(36) = 4420 = 1+2+3+10+11+12+13+20+21+22+30+31+100+101+102+103+110+111+112+113+120+121+122+130+200+201+202+210+211+212+220+221+300+301+310+311
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Programs

Mathematica

Accumulate[Select[Range[0,1200],IntegerReverse[#^2]==IntegerReverse[#]^2&]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 02 2017 *)