A033298 a(n+1) = a(n) + sum of digits of a(n)^2, with a(1) = 1.

1, 2, 6, 15, 24, 42, 60, 69, 87, 114, 141, 168, 186, 213, 240, 258, 285, 303, 330, 348, 357, 384, 411, 438, 465, 483, 510, 519, 546, 573, 600, 609, 636, 663, 699, 726, 753, 780, 798, 825, 852, 879, 906, 933, 969, 1005, 1014, 1041, 1068, 1086

Offset: 1

Author

Miklos SZABO (mike(AT)ludens.elte.hu)

Keywords

• nonn
• base
• easy
• less

Examples

			a(6) = 42 as a(5) = 24 giving a(6) = 24 + (sum of digits of 24^2 = 576) = 24 + 5 + 7 + 6 = 42. - _David A. Corneth_, Jun 26 2022
		

Links

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

Crossrefs

Cf. A047892, A004207, A007953.

Partial sums of A139417.

Programs

Mathematica

NestList[#+Total[IntegerDigits[#^2]]&,1,50] (* Harvey P. Dale, Sep 21 2023 *)

PARI

first(n) = {n=max(n,1); my(res=vector(n)); res[1] = 1; for(i = 2, n, res[i] = res[i-1] + sumdigits(res[i-1]^2)); res} \\ David A. Corneth, Jun 26 2022