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A258876 Integers n such that both n and prime(n) have the same digital root. 6
25, 32, 46, 56, 70, 88, 92, 98, 100, 113, 121, 130, 145, 146, 152, 175, 176, 182, 185, 206, 209, 212, 218, 227, 236, 239, 244, 248, 274, 293, 295, 301, 316, 317, 320, 323, 331, 338, 350, 352, 355, 362, 377, 386, 394, 397, 398, 406, 409, 413, 439 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Integers n such that A010888(n) = A038194(n).

Conjecture: a(n) ~ 9n. - Charles R Greathouse IV, Jun 17 2015

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

EXAMPLE

Both 25 and prime(25) = 97 have 7 for a digital root.

Both 32 and prime(32) = 131 have 5 for a digital root.

MATHEMATICA

Reap[Do[If[FixedPoint[Total[IntegerDigits[#]] &, n] == Mod[Prime[n], 9], Sow[n]], {n, 439}]][[2, 1]] (* Seidov *)

Select[Range[500], Mod[#, 9] == Mod[Prime[#], 9] &] (* Alonso del Arte, Jun 17 2015 *)

PROG

(PARI) isok(n) = (n % 9) == (prime(n) % 9); \\ Michel Marcus, Jun 17 2015

(PARI) n=0; forprime(p=2, 1e4, if((p-n++)%9==0, print1(n", "))) \\ Charles R Greathouse IV, Jun 17 2015

CROSSREFS

Cf. A010888, A038194.

Sequence in context: A092100 A172007 A107258 * A263029 A225418 A035140

Adjacent sequences:  A258873 A258874 A258875 * A258877 A258878 A258879

KEYWORD

base,nonn

AUTHOR

Zak Seidov, Jun 13 2015

STATUS

approved

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Last modified September 22 16:41 EDT 2019. Contains 327311 sequences. (Running on oeis4.)