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A174597
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Numbers n with the property that their digital sum is equal to the number of letters in n when spelled out in English.
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1
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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
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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Example: 16 is in the list because 1+6 = 7 = number of letters in sixteen.
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LINKS
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PROG
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(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 (""));
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CROSSREFS
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KEYWORD
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base,nonn,word
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AUTHOR
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STATUS
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approved
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