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A140058
Numbers > 24 that are congruent to {5,6,7,8,9} mod 10.
0
25, 26, 27, 28, 29, 35, 36, 37, 38, 39, 45, 46, 47, 48, 49, 55, 56, 57, 58, 59, 65, 66, 67, 68, 69, 75, 76, 77, 78, 79, 85, 86, 87, 88, 89, 95, 96, 97, 98, 99, 105, 106, 107, 108, 109, 115, 116, 117, 118, 119, 125, 126, 127, 128, 129, 135, 136, 137, 138, 139, 145, 146
OFFSET
1,1
COMMENTS
Amounts in cents of coins in denominations 1, 5 and 10 cents that must include change for a 25-cent coin. Regarding currently-minted US coins, note that the 25-cent quarter is the only denomination for which a smaller denomination exists (the 10-cent dime) which is not a divisor. As a result, an amount that may consist only of any number of dimes and up to four 1-cent pennies does not guarantee change for a quarter.
FORMULA
a(n) = 10 + a(n-5) for n >= 6.
From Chai Wah Wu, Jun 10 2016: (Start)
a(n) = a(n-1) + a(n-5) - a(n-6) for n > 6.
G.f.: x*(-19*x^5 + x^4 + x^3 + x^2 + x + 25)/(x^6 - x^5 - x + 1). (End)
a(n) = 25 + ((n-1) mod 5) + 10*floor((n-1)/5). - Wesley Ivan Hurt, Nov 03 2016
MATHEMATICA
Table[25 + Mod[n - 1, 5] + 10*Floor[(n - 1)/5], {n, 50}] (* Wesley Ivan Hurt, Nov 03 2016 *)
PROG
(PARI) is(n) = n > 24 && n % 10 > 4 \\ Felix Fröhlich, Nov 03 2016
(Magma) [n : n in [25..150] | n mod 10 in [5..9]]; // Vincenzo Librandi, Nov 04 2016
CROSSREFS
Cf. A130734.
Sequence in context: A135218 A133507 A046511 * A199992 A242221 A186538
KEYWORD
easy,nonn
AUTHOR
Rick L. Shepherd, May 05 2008
STATUS
approved