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A065207 Two 'Reverse and Add' steps are needed to reach a palindrome. 4
19, 28, 37, 39, 46, 48, 49, 57, 58, 64, 67, 73, 75, 76, 82, 84, 85, 91, 93, 94, 109, 119, 129, 139, 149, 150, 152, 153, 154, 159, 160, 162, 163, 169, 170, 172, 173, 179, 189, 208, 218, 219, 228, 229, 238, 239, 248, 250, 251, 253, 258, 259, 260, 261, 268, 269 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The number of steps starts at 0, so palindromes (cf. A002113) are excluded.

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

Index entries for sequences related to Reverse and Add!

PROG

(ARIBAS): revadd_steps(2, 58). For the definition of function revadd_steps see A065206.

(PARI) Rev(x)= { local(d, r=0); while (x>0, d=x-10*(x\10); x\=10; r=r*10 + d); return(r) } digitsIn(x)= { local(d); if (x==0, return(1)); d=1 + log(x)\log(10); if (10^d == x, d++, if (10^(d-1) > x, d--)); return(d) } Palin(x)= { local(d, e, f, i, t, y); if (x==0, return(1)); y=x; d=digitsIn(x); t=10^(d - 1); for (i=1, d\2, f=y-10*(y\10); y\=10; e=x\t; x-=t*e; t/=10; if (e!=f, return(0)) ); return(1) } { n=0; for (m = 0, 10^9, p=m; b=1; for (i=1, 2, if (Palin(p), b=0; break); p=Rev(p) + p); if (b && Palin(p), write("b065207.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Oct 14 2009

CROSSREFS

Cf. A002113, A015977, A065206.

Sequence in context: A173639 A091448 A067777 * A084364 A094677 A052224

Adjacent sequences:  A065204 A065205 A065206 * A065208 A065209 A065210

KEYWORD

nonn,base

AUTHOR

Klaus Brockhaus, Oct 21 2001

EXTENSIONS

Offset changed from 0 to 1 by Harry J. Smith, Oct 14 2009

STATUS

approved

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Last modified October 16 08:15 EDT 2019. Contains 328051 sequences. (Running on oeis4.)