|
| |
|
|
A028837
|
|
Iterated sum of digits of n is a square.
|
|
2
| |
|
|
1, 4, 9, 10, 13, 18, 19, 22, 27, 28, 31, 36, 37, 40, 45, 46, 49, 54, 55, 58, 63, 64, 67, 72, 73, 76, 81, 82, 85, 90, 91, 94, 99, 100, 103, 108, 109, 112, 117, 118, 121, 126, 127, 130, 135, 136, 139, 144, 145, 148, 153, 154, 157, 162, 163, 166, 171, 172, 175, 180
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
FORMULA
| a(n) = a(n-3)+9. If n is a multiple of 3 then a(n) = 3n, otherwise a(n) = 3n-2. Numbers of form {0, 1, 4} modulo 9 - Henry Bottomley (se16(AT)btinternet.com), Jun 30 2000
|
|
|
EXAMPLE
| E.g. 58 -> 5+8 = 13 -> 1+3 = 4 is a square.
|
|
|
CROSSREFS
| Cf. A010888, A028839, A028845.
Sequence in context: A038029 A197039 A020672 * A178241 A028839 A141833
Adjacent sequences: A028834 A028835 A028836 * A028838 A028839 A028840
|
|
|
KEYWORD
| nonn,base
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
|
|
|
EXTENSIONS
| More terms from Patrick De Geest (pdg(AT)worldofnumbers.com), Jun 15 1999.
|
| |
|
|
