A174597 Numbers n with the property that their digital sum is equal to the number of letters in n when spelled out in English.

4, 16, 36, 38, 45, 50, 54, 62, 70, 74, 81, 83, 299, 489, 569, 596, 598, 649, 666, 668, 687, 695, 709, 759, 779, 786, 788, 797, 849, 866, 868, 887, 895, 907, 919, 939, 946, 948, 957, 965, 977, 980, 984, 992, 4099

Offset

1,1

Comments

Example: 16 is in the list because 1+6 = 7 = number of letters in sixteen.

Links

Felix Fröhlich, Table of n, a(n) for n = 1..7414

Prog

(PARI)
v1 = ["one", "two", "three", "four", "five", "six", "seven", "eight", "nine"];
v2 = ["eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"];
v3 = ["ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"];
conv(n) = {if (n >= 10^12, error("too big for this program"));
if (n >= 10^9, return (concat(concat(conv(n\10^6), "billion"), conv(n % 10^9))));
if (n >= 10^6, return (concat(concat(conv(n\10^6), "million"), conv(n % 10^6))));
if (n >= 10^3, return (concat(concat(conv(n\10^3), "thousand"), conv(n % 10^3))));
if (n >= 10^2, return (concat(concat(conv(n\100), "hundred"), conv(n % 100))));
if (n >= 20, return (concat(v3[n\10], conv(n%10))); );
if (n >= 10, if (n==10, return(v3[n\10]), return(v2[n % 10])); );
if (n, return(v1[n]), return (""));
} \\ after Michel Marcus in A303475
is(n) = #conv(n)==sumdigits(n) \\ Felix Fröhlich, Oct 13 2019

Crossrefs

Cf. A007953 (digital sum).

Sequence in context: A292208 A104125 A014727 * A044065 A281795 A063540

Adjacent sequences: A174594 A174595 A174596 * A174598 A174599 A174600

Keyword

base,nonn,word

Author

Claudio Meller, Mar 23 2010

Status

approved