A225017 - OEIS

A225017

Odd part of digit sum of 5^n divided by maximal possible power of 5.

1, 1, 7, 1, 13, 11, 19, 23, 1, 13, 1, 19, 7, 23, 17, 11, 29, 7, 1, 59, 61, 31, 67, 37, 41, 77, 79, 89, 17, 83, 91, 13, 53, 89, 103, 23, 109, 13, 31, 67, 13, 137, 29, 149, 151, 29, 7, 1, 29, 79, 151, 19, 13, 119, 127, 167, 49, 43, 211, 191, 199, 97, 187, 17, 83

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

COMMENTS

Does the sequence contain every prime greater than 5?

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..10000 (terms n = 0..999 from Peter J. C. Moses)

FORMULA

a(n) = A132740(A055566(n)). - Michel Marcus, Dec 10 2018

MAPLE

a:= proc(n) local m, r; m, r:= 0, 5^n;

while r>0 do m:= m+irem(r, 10, 'r') od;

while irem(m, 2, 'r')=0 do m:=r od;

while irem(m, 5, 'r')=0 do m:=r od; m

end:

seq(a(n), n=0..80); # Alois P. Heinz, Apr 24 2013

MATHEMATICA

Map[#/(2^IntegerExponent[#, 2] 5^IntegerExponent[#, 5])&[Total[ IntegerDigits[5^#]]]&, Range[0, 99]] (* Peter J. C. Moses, Apr 24 2013 *)

PROG

(PARI) a(n) = my(x = sumdigits(5^n)); x/5^valuation(x, 5) >> valuation(x, 2); \\ Michel Marcus, Dec 10 2018

CROSSREFS

Cf. A055566, A132740.

Sequence in context: A060393 A060394 A203810 * A268919 A040055 A317016

Adjacent sequences: A225014 A225015 A225016 * A225018 A225019 A225020

KEYWORD

nonn,base

AUTHOR

Vladimir Shevelev, Apr 24 2013

STATUS

approved